Image manipulation method for camera

ABSTRACT

A handheld camera comprises a sensor adapted to sense an image, a camera manager for controlling the sensing of the image, an image processing manager for manipulating the image, a print manager for controlling printing of the manipulated image, and a guillotine adapted to cut a print media on which the manipulated image is printed from a print roll. The print manager is operable to activate the guillotine upon receipt of a signal indicative of an attempt to dispense the print media at a rate greater than that of a print roll drive system for dispensing the print media.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Continuation application of U.S. Ser. No.10/729,159 filed on 8 Dec. 2003 which is a Continuation application ofU.S. Ser. No. 09/113,057 filed on Jul. 10, 1998. The contents of Ser.Nos. 10/729,159 and 09/113,057 are incorporated herein in entirety byreference.

FIELD OF THE INVENTION

The present disclosure relates to a data processing method and apparatusand, in particular, discloses a camera operable to manipulate an imagetaken by a camera, and a method of manipulating the image.

BACKGROUND OF THE INVENTION

Camera systems that provide for the creation of instant images on demandin a similar manner to an instant Polaroid™ camera are known. Suchsystems include means for insertion of a card to manipulate the printedimage to produce interesting effects.

SUMMARY OF THE INVENTION

According to one aspect of the present disclosure, a method of operatinga handheld camera comprises causing a sensor to sense an image,supplying predetermined data to an input of the camera via a card onwhich the predetermined data is disposed, and causing a processingsystem to obtain the image from the sensor, determine a card image inaccordance with signals received from the input, rotate the card imagein accordance with a skew of the card with respect to the input, andmanipulate the image in accordance with the predetermined data tothereby generate a manipulated image.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of thepresent invention, preferred forms of the invention will now bedescribed, by way of example only, with reference to the accompanyingdrawings in which:

FIG. 1 illustrates an Artcam device constructed in accordance with thepreferred embodiment;

FIG. 2 is a schematic block diagram of the main Artcam electroniccomponents;

FIG. 3 is a schematic block diagram of the Artcam Central Processor;

FIG. 3( a) illustrates the VLIW Vector Processor in more detail;

FIG. 4 illustrates a pixel data configuration;

FIG. 5 illustrates a pixel processing process;

FIG. 6 illustrates a schematic block diagram of the display controller;

FIG. 7 illustrates the image pyramid storage format;

FIG. 8 illustrates a time line of the process of sampling an Artcard;

FIG. 9 illustrates the super sampling process;

FIG. 10 illustrates the process of reading a rotated Artcard;

FIG. 11 illustrates a flow chart of the steps necessary to decode anArtcard;

FIG. 12 illustrates an enlargement of the left hand corner of a singleArtcard;

FIG. 13 illustrates a single target for detection;

FIG. 14 illustrates the method utilised to detect targets;

FIG. 15 illustrates the process of centroid drift;

FIG. 16 shows one form of centroid lookup table;

FIG. 17 illustrates the centroid updating process;

FIG. 18 illustrates a delta processing lookup table utilised in thepreferred embodiment;

FIG. 19 illustrates the process of unscrambling Artcard data;

FIG. 20 illustrates an actual implementation of a diffuse calculation;

FIG. 21 illustrates an example illumination calculation for a singleinfinite light source; image with an associated bump-map;

FIG. 22 illustrates the logical layout of a single printhead;

FIG. 23 illustrates the process of rotation of a Lab image;

FIG. 24 illustrates the process of generating an 8 bit dot output;

FIG. 25 illustrates a perspective view of the card reader;

FIG. 26 illustrates a perspective view of the print roll and print head;

FIG. 27 illustrates a first exploded perspective view of the print roll;

FIG. 28 illustrates a second exploded perspective view of the printroll;

FIG. 29 illustrates the print roll authentication chip;

FIG. 30 illustrates an enlarged view of the print roll authenticationchip;

FIG. 31 is an exploded perspective, in section, of the print head inksupply mechanism;

FIG. 32 is a bottom perspective of the ink head supply unit;

FIG. 33 is a top perspective of the ink head supply unit;

FIG. 34 is a top side sectional view of the ink head supply unit;

FIG. 35 illustrates a perspective view of a small portion of the printhead;

FIG. 36 illustrates is an exploded perspective of the print head unit;

FIG. 37 illustrates the backing portion of a postcard print roll;

FIG. 38 illustrates the corresponding front image on the postcard printroll after printing out images;

FIG. 39 illustrates a form of print roll ready for purchase by aconsumer;

FIG. 40 illustrates a layout of the software/hardware modules of theoverall Artcam application;

FIG. 41 illustrates a layout of the software/hardware modules of theCamera Manager;

FIG. 42 illustrates a layout of the software/hardware modules of theImage Processing Manager;

FIG. 43 illustrates a layout of the software/hardware modules of thePrinter Manager;

FIG. 44 illustrates a layout of the software/hardware modules of theImage Processing Manager;

FIG. 45 illustrates a layout of the software/hardware modules of theFile Manager.

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS I. Digital ImageProcessing Camera System

The digital image processing camera system constructed in accordancewith the preferred embodiment is as illustrated in FIG. 1. The cameraunit 1 includes means for the insertion of an integral print roll (notshown). The camera unit 1 can include an area image sensor 2 whichsensors an image 3 for captured by the camera. Optionally, the secondarea image sensor can be provided to also image the scene 3 and tooptionally provide for the production of stereographic output effects.

The camera 1 can include an optional color display 5 for the display ofthe image being sensed by the sensor 2. When a simple image is beingdisplayed on the display 5, the button 6 can be depressed resulting inthe printed image 8 being output by the camera unit 1. A series ofcards, herein after known as “Artcards” 9 contain, on one surfaceencoded information and on the other surface, contain an image distortedby the particular effect produced by the Artcard 9. The Artcard 9 isinserted in an Artcard reader 10 in the side of camera 1 and, uponinsertion, results in output image 8 being distorted in the same manneras the distortion appearing on the surface of Artcard 9. Hence, by meansof this simple user interface a user wishing to produce a particulareffect can insert one of many Artcards 9 into the Artcard reader 10 andutilize button 19 to take a picture of the image 3 resulting in acorresponding distorted output image 8.

The camera unit 1 can also include a number of other control button 13,14 in addition to a simple LCD output display 15 for the display ofinformative information including the number of printouts left on theinternal print roll on the camera unit. Additionally, different outputformats can be controlled by CHP switch 17.

Turning now to FIG. 2, there is illustrated a schematic view of theinternal hardware of the camera unit 1. The following components areincluded in the internal hardware of the camera unit 1:

Artcam Central Processor 31

The ACP 31 is preferably implemented as a complex, high speed, CMOSsystem on-a-chip. Utilising standard cell design with some full customregions is recommended. Fabrication on a 0.25μ CMOS process will providethe density and speed required, along with a reasonably small die area.The functions provided by the ACP 31 include:

-   -   1. Control and digitization of the area image sensor 2. A 3D        stereoscopic version of the ACP requires two area image sensor        interfaces with a second optional image sensor 4 being provided        for stereoscopic effects.    -   2. Area image sensor compensation, reformatting, and image        enhancement.    -   3. Memory interface and management to a memory store 33.    -   4. Interface, control, and analog to digital conversion of an        Artcard reader linear image sensor 34 which is provided for the        reading of data from the Artcards 9.    -   5. Extraction of the raw Artcard data from the digitized and        encoded Artcard image.    -   6. Reed-Solomon error detection and correction of the Artcard        encoded data. The encoded surface of the Artcard 9 includes        information on how to process an image to produce the effects        displayed on the image distorted surface of the Artcard 9. This        information is in the form of a script, hereinafter known as a        “Vark script”. The Vark script is utilised by an interpreter        running within the ACP 31 to produce the desired effect.    -   7. Interpretation of the Vark script on the Artcard 9.    -   8. Performing image processing operations as specified by the        Vark script.    -   9. Controlling various motors for the paper transport 36, zoom        lens 38, autofocus 39 and Artcard driver 37.    -   10. Controlling a guillotine actuator 40 for the operation of a        guillotine 41 for the cutting of photographs 8 from print roll        42.    -   11. Half-toning of the image data for printing.    -   12. Providing the print data to a print-head 44 at the        appropriate times.    -   13. Controlling the print head 44.    -   14. Controlling the ink pressure feed to print-head 44.    -   15. Controlling optional flash unit 56.    -   16. Reading and acting on various sensors in the camera,        including camera orientation sensor 46, autofocus 47 and Artcard        insertion sensor 49.    -   17. Reading and acting on the user interface buttons 6, 13, 14.    -   18. Controlling the status display 15.    -   19. Providing viewfinder and preview images to the color display        5.    -   20. Control of the system power consumption, including the ACP        power consumption via power management circuit 51.    -   21. Providing external communications 52 to general purpose        computers (using part USB).    -   22. Reading and storing information in a printing roll        authentication chip 53.    -   23. Reading and storing information in a camera authentication        chip 54.    -   24. Communicating with an optional mini-keyboard 57 for text        modification.

Quartz Crystal 58

A quartz crystal 58 is used as a frequency reference for the systemclock. As the system clock is very high, the ACP 31 includes a phaselocked loop clock circuit to increase the frequency derived from thecrystal 58.

Area Image Sensor 2

The area image sensor 2 converts an image through its lens into anelectrical signal. It can either be a charge coupled device (CCD) or anactive pixel sensor (APS) CMOS image sector. At present, available CCD'snormally have a higher image quality, however, there is currently muchdevelopment occurring in CMOS imagers. CMOS imagers are eventuallyexpected to be substantially cheaper than CCD's have smaller pixelareas, and be able to incorporate drive circuitry and signal processing.They can also be made in CMOS fabs, which are transitioning to 12″wafers. CCD's are usually built in 6″ wafer fabs, and economics may notallow a conversion to 12″ fabs. Therefore, the difference in fabricationcost between CCD's and CMOS imagers is likely to increase, progressivelyfavoring CMOS imagers. However, at present, a CCD is probably the bestoption.

The Artcam unit will produce suitable results with a 1,500×1,000 areaimage sensor. However, smaller sensors, such as 750×500, will beadequate for many markets. The Artcam is less sensitive to image sensorresolution than are conventional digital cameras. This is because manyof the styles contained on Artcards 9 process the image in such a way asto obscure the lack of resolution. For example, if the image isdistorted to simulate the effect of being converted to animpressionistic painting, low source image resolution can be used withminimal effect. Further examples for which low resolution input imageswill typically not be noticed include image warps which produce highdistorted images, multiple miniature copies of the of the image (eg.passport photos), textural processing such as bump mapping for a baserelief metal look, and photo-compositing into structured scenes.

This tolerance of low resolution image sensors may be a significantfactor in reducing the manufacturing cost of an Artcam unit 1 camera. AnArtcam with a low cost 750×500 image sensor will often produce superiorresults to a conventional digital camera with a much more expensive1,500×1,000 image sensor.

Stereoscopic 3D Image Sensor 4

An embodiment of the Artcam unit 1 adapted for 3D stereoscopic operationincludes an additional image sensor 4, for stereoscopic operation. Thisimage sensor is identical to the main image sensor. The circuitry todrive the optional image sensor may be included as a standard part ofthe ACP chip 31 to reduce incremental design cost. Alternatively, aseparate 3D Artcam ACP can be designed. This option will reduce themanufacturing cost of a mainstream single sensor Artcam.

Print Roll Authentication Chip 53

A small chip 53 is included in each print roll 42. This chip replacedthe functions of the bar code, optical sensor and wheel, and ISO/ASAsensor on other forms of camera film units such as Advanced PhotoSystems film cartridges.

The authentication chip also provides other features:

-   -   1. The storage of data rather than that which is mechanically        and optically sensed from APS rolls    -   2. A remaining media length indication, accurate to high        resolution.    -   3. Authentication Information to prevent inferior clone print        roll copies.

The authentication chip 53 contains 1024 bits of Flash memory, of which128 bits is an authentication key, and 512 bits is the authenticationinformation. Also included is an encryption circuit to ensure that theauthentication key cannot be accessed directly.

Print-Head 44

The Artcam unit 1 can utilize any suitable color print technologyPreferably, an ink jet head used in the Artcam unit 1 has the followingspecifications

Image type Bi-level, dithered Color CMY Process Color Resolution 1600dpi Print head length ‘Page-width’ (100 mm) Print speed 2 seconds perphoto

Paper Transport Motor 36

The paper transport motor 36 moves the paper from within the print roll42 past the print head at a relatively constant rate. The motor 36 is aminiature motor geared down to an appropriate speed to drive rollerswhich move the paper. A high quality motor and mechanical gears arerequired to achieve high image quality, as mechanical rumble or othervibrations will affect the printed dot row spacing.

Paper Transport Motor Driver 60

The motor driver 60 is a small circuit which amplifies the digital motorcontrol signals from the APC 31 to levels suitable for driving the motor36.

Paper Pull Sensor

A paper pull sensor 50 detects a user's attempt to pull a photo from thecamera unit during the printing process. The APC 31 reads this sensor50, and activates the guillotine 41 if the condition occurs. The paperpull sensor 50 is incorporated to make the camera more ‘foolproof’ inoperation. Were the user to pull the paper out forcefully duringprinting, the print mechanism 44 or print roll 42 may (in extreme cases)be damaged. Since it is acceptable to pull out the ‘pod’ from a Polaroidtype camera before it is fully ejected, the public has been ‘trained’ todo this. Therefore, they are unlikely to heed printed instructions notto pull the paper.

The Artcam preferably restarts the photo print process after theguillotine 41 has cut the paper after pull sensing.

The pull sensor can be implemented as a strain gauge sensor, or as anoptical sensor detecting a small plastic flag which is deflected by thetorque that occurs on the paper drive rollers when the paper is pulled.The latter implementation is recommendation for low cost.

Paper Guillotine Actuator 40

The paper guillotine actuator 40 is a small actuator which causes theguillotine 41 to cut the paper either at the end of a photograph, orwhen the paper pull sensor 50 is activated.

The guillotine actuator 40 is a small circuit which amplifies aguillotine control signal from the APC tot the level required by theactuator 41.

Artcard 9

The Artcard 9 is a program storage medium for the Artcam unit. As notedpreviously, the programs are in the form of Vark scripts. Vark is apowerful image processing language especially developed for the Artcamunit. Each Artcard 9 contains one Vark script, and thereby defines oneimage processing style.

By utilizing the language constructs as defined by the created language,new affects on arbitrary images can be created and constructed forinexpensive storage on Artcard and subsequent distribution to cameraowners. Further, on one surface of the card can be provided an exampleillustrating the effect that a particular VARK script, stored on theother surface of the card, will have on an arbitrary captured image.

By utilizing such a system, camera technology can be distributed withouta great fear of obsolescence in that, provided a VARK interpreter isincorporated in the camera device, a device independent scenario isprovided whereby the underlying technology can be completely varied overtime. Further, the VARK scripts can be updated as new filters arecreated and distributed in an inexpensive manner, such as via simplecards for card reading.

The Artcard 9 is a piece of thin white plastic with the same format as acredit card (86 mm long by 54 mm wide). The Artcard is printed on bothsides using a high resolution ink jet printer. The inkjet printertechnology is assumed to be the same as that used in the Artcam, with1600 dpi (63 dpmm) resolution. A major feature of the Artcard 9 is lowmanufacturing cost. Artcards can be manufactured at high speeds as awide web of plastic film. The plastic web is coated on both sides with ahydrophilic dye fixing layer. The web is printed simultaneously on bothsides using a ‘pagewidth’ color ink jet printer. The web is then cut andpunched into individual cards. On one face of the card is printed ahuman readable representation of the effect the Artcard 9 will have onthe sensed image. This can be simply a standard image which has beenprocessed using the Vark script stored on the back face of the card.

On the back face of the card is printed an array of dots which can bedecoded into the Vark script that defines the image processing sequence.The print area is 80 mm×50 mm, giving a total of 15,876,000 dots. Thisarray of dots could represent at least 1.89 Mbytes of data. To achievehigh reliability, extensive error detection and correction isincorporated in the array of dots. This allows a substantial portion ofthe card to be defaced, worn, creased, or dirty with no effect on dataintegrity. The data coding used is Reed-Solomon coding, with half of thedata devoted to error correction. This allows the storage of 967 Kbytesof error corrected data on each Artcard 9.

Linear Image Sensor 34

The Artcard linear sensor 34 converts the aforementioned Artcard dataimage to electrical signals. As with the area image sensor 2, 4, thelinear image sensor can be fabricated using either CCD or APS CMOStechnology. The active length of the image sensor 34 is 50 mm, equal tothe width of the data array on the Artcard 9. To satisfy Nyquist'ssampling theorem, the resolution of the linear image sensor 34 must beat least twice the highest spatial frequency of the Artcard opticalimage reaching the image sensor. In practice, data detection is easierif the image sensor resolution is substantially above this. A resolutionof 4800 dpi (189 dpmm) is chosen, giving a total of 9,450 pixels. Thisresolution requires a pixel sensor pitch of 5.3 μm. This can readily beachieved by using four staggered rows of 20 μm pixel sensors.

The linear image sensor is mounted in a special package which includes aLED 65 to illuminate the Artcard 9 via a light-pipe (not shown).

The Artcard reader light-pipe can be a molded light-pipe which hasseveral function:

-   -   1. It diffuses the light from the LED over the width of the card        using total internal reflection facets.    -   2. It focuses the light onto a 16 μm wide strip of the Artcard 9        using an integrated cylindrical lens.    -   3. It focuses light reflected from the Artcard onto the linear        image sensor pixels using a molded array of microlenses.

Artcard Reader Motor 37

The Artcard reader motor propels the Artcard past the linear imagesensor 34 at a relatively constant rate. As it may not be cost effectiveto include extreme precision mechanical components in the Artcardreader, the motor 37 is a standard miniature motor geared down to anappropriate speed to drive a pair of rollers which move the Artcard 9.The speed variations, rumble, and other vibrations will affect the rawimage data as circuitry within the APC 31 includes extensivecompensation for these effects to reliably read the Artcard data. Themotor 37 is driven in reverse when the Artcard is to be ejected.

Artcard Motor Driver 61

The Artcard motor driver 61 is a small circuit which amplifies thedigital motor control signals from the APC 31 to levels suitable fordriving the motor 37.

Card Insertion Sensor 49

The card insertion sensor 49 is an optical sensor which detects thepresence of a card as it is being inserted in the card reader 34. Upon asignal from this sensor 49, the APC 31 initiates the card readingprocess, including the activation of the Artcard reader motor 37.

Card Eject Button 16

A card eject button 16 (FIG. 1) is used by the user to eject the currentArtcard, so that another Artcard can be inserted. The APC 31 detects thepressing of the button, and reverses the Artcard reader motor 37 toeject the card.

Card Status Indicator 66

A card status indicator 66 is provided to signal the user as to thestatus of the Artcard reading process. This can be a standard bi-color(red/green) LED. When the card is successfully read, and data integrityhas been verified, the LED lights up green continually. If the card isfaulty, then the LED lights up red.

If the camera is powered from a 1.5 V instead of 3V battery, then thepower supply voltage is less than the forward voltage drop of the greedLED, and the LED will not light. In this case, red LEDs can be used, orthe LED can be powered from a voltage pump which also powers othercircuits in the Artcam which require higher voltage.

64 Mbit DRAM 33

To perform the wide variety of image processing effects, the camerautilizes 8 Mbytes of memory 33. This can be provided by a single 64 Mbitmemory chip. Of course, with changing memory technology increased Dramstorage sizes may be substituted.

High speed access to the memory chip is required. This can be achievedby using a Rambus DRAM (burst access rate of 500 Mbytes per second) orchips using the new open standards such as double data rate (DDR) SDRAMor Synclink DRAM.

Camera Authentication Chip

The camera authentication chip 54 is identical to the print rollauthentication chip 53, except that it has different information storedin it. The camera authentication chip 54 has three main purposes:

-   -   1. To provide a secure means of comparing authentication codes        with the print roll authentication chip;    -   2. To provide storage for manufacturing information, such as the        serial number of the camera;    -   3. To provide a small amount of non-volatile memory for storage        of user information.

Displays

The Artcam includes an optional color display 5 and small status display15. Lowest cost consumer cameras may include a color image display, suchas a small TFT LCD 5 similar to those found on some digital cameras andcamcorders. The color display 5 is a major cost element of theseversions of Artcam, and the display 5 plus back light are a major powerconsumption drain. The status display 15 is a small passive segmentbased LCD, similar to those currently provided on silver halide anddigital cameras. Its main function is to show the number of printsremaining in the print roll 42 and icons for various standard camerafeatures, such as flash and battery status. The color display 5 is afull motion image display which operates as a viewfinder, as averification of the image to be printed, and as a user interfacedisplay. The cost of the display 5 is approximately proportional to itsarea, so large displays (say 4″ diagonal) unit will be restricted toexpensive versions of the Artcam unit. Smaller displays, such as colorcamcorder viewfinder TFT's at around 1″, may be effective for mid-rangeArtcams.

Zoom Lens (Not Shown)

The Artcam can include a zoom lens. This can be a standardelectronically controlled zoom lens, identical to one which would beused on a standard electronic camera, and similar to pocket camera zoomlenses. A referred version of the Artcam unit may include standardinterchangeable 35 mm SLR lenses.

Autofocus Motor 39

The autofocus motor 39 changes the focus of the zoom lens. The motor isa miniature motor geared down to an appropriate speed to drive theautofocus mechanism.

Autofocus Motor Driver 63

The autofocus motor driver 63 is a small circuit which amplifies thedigital motor control signals from the APC 31 to levels suitable fordriving the motor 39.

Zoom Motor 38

The zoom motor 38 moves the zoom front lenses in and out. The motor is aminiature motor geared down to an appropriate speed to drive the zoommechanism.

Zoom Motor Driver 62

The zoom motor driver 62 is a small circuit which amplifies the digitalmotor control signals from the APC 31 to levels suitable for driving themotor.

Communications

The ACP 31 contains a universal serial bus (USB) interface 52 forcommunication with personal computers. Not all Artcam models areintended to include the USB connector. However, the silicon arearequired for a USB circuit 52 is small, so the interface can be includedin the standard ACP.

Optional Keyboard 57

The Artcam unit may include an optional miniature keyboard 57 forcustomizing text specified by the Artcard. Any text appearing in anArtcard image may be editable, even if it is in a complex metallic 3Dfont. The miniature keyboard includes a single line alphanumeric LCD todisplay the original text and edited text. The keyboard may be astandard accessory.

The ACP 31 contains a serial communications circuit for transferringdata to and from the miniature keyboard.

Power Supply

The Artcam unit uses a battery 48. Depending upon the Artcam options,this is either a 3V Lithium cell, 1.5 V AA alkaline cells, or otherbattery arrangement.

Power Management Unit 51

Power consumption is an important design constraint in the Artcam. It isdesirable that either standard camera batteries (such as 3V lithiumbatters) or standard AA or AAA alkaline cells can be used. While theelectronic complexity of the Artcam unit is dramatically higher than 35mm photographic cameras, the power consumption need not becommensurately higher. Power in the Artcam can be carefully managed withall units being turned off when not in use.

The most significant current drains are the ACP 31, the area imagesensors 2,4, the printer 44 various motors, the flash unit 56, and theoptional color display 5:

-   -   1. ACP: If fabricated using 0.25 μm CMOS, and running on 1.5V,        the ACP power consumption can be quite low. Clocks to various        parts of the ACP chip can be quite low. Clocks to various parts        of the ACP chip can be turned off when not in use, virtually        eliminating standby current consumption. The ACP will only fully        used for approximately 4 seconds for each photograph printed.    -   2. Area image sensor: power is only supplied to the area image        sensor when the user has their finger on the button.    -   3. The printer power is only supplied to the printer when        actually printing. This is for around 2 seconds for each        photograph. Even so, suitably lower power consumption printing        should be used.    -   4. The motors required in the Artcam are all low power miniature        motors, and are typically only activated for a few seconds per        photo.    -   5. The flash unit 45 is only used for some photographs. Its        power consumption can readily be provided by a 3V lithium        battery for a reasonably battery life.    -   6. The optional color display 5 is a major current drain for two        reasons: it must be on for the whole time that the camera is in        use, and a backlight will be required if a liquid crystal        display is used. Cameras which incorporate a color display will        require a larger battery to achieve acceptable batter life.

Flash Unit 56

The flash unit 56 can be a standard miniature electronic flash forconsumer cameras.

II. ACP 31 in Detail

The ACP 31 is described now with reference to FIG. 3, which illustratesthe Artcam Central Processor (ACP) 31 in greated detail. The ArtcamCentral Processor provides all of the processing power for Artcam. It isdesigned for a 0.25 micron CMOS process, with approximately 1.5 milliontransistors and an area of around 50 mm². The ACP 31 is a complexdesign, but design effort can be reduced by the use of datapathcompilation techniques, macrocells, and IP cores. The ACP 31 includes:

-   -   1. RISC CPU core 72    -   2. 4 Mbyte Flash memory 70 for program storage    -   3. Direct RAMbus interface 81    -   4. JTAG Interface 85    -   5. USB serial interface 52    -   6. Parallel interface 67    -   7. VLIW Input and Output FIFOs 78, 79    -   8. 4 way parallel VLIW Vector Processor 74    -   9. CMOS image sensor interface 83    -   10. Color TFT LCD interface 88    -   11. Artcard Interface 87

The RISC CPU, Direct RAMbus interface 81, CMOS sensor interface 83 andUSB serial interface 52 can be vendor supplied cores. The ACP 31 isintended to run at a clock speed of 200 MHz on 3V externally and 1.5Vinternally to minimize power consumption. The CPU core needs only to runat 100 MHz.

1. RISC CPU Core (CPU) 72

The ACP 31 incorporates a 32 bit RISC CPU 72 to run the Vark imageprocessing language interpreter and to perform Artcam's generaloperating system duties. A wide variety of CPU cores are suitable: itcan be any processor core with sufficient processing power to performthe required core calculations and control functions fast enough to metconsumer expectations. Examples of suitable cores are: MIPS R4000 corefrom LSI Logic, StrongARM core. There is no need to maintain instructionset continuity between different Artcam models. Artcard compatibility ismaintained irrespective of future processor advances and changes,because the Vark interpreter is simply re-compiled for each newinstruction set. The ACP 31 architecture is therefore also free toevolve. Different ACP 31 chip designs may be fabricated by differentmanufacturers, without requiring to license or port the CPU core. Thisdevice independence avoids the chip vendor lock-in such as has occurredin the PC market with Intel. The CPU operates at 100 MHz, with a singlecycle time of 10 ns. It must be fast enough to run the Vark interpreter,although the VLIW Vector Processor 74 is responsible for most of thetime-critical operations.

2. 4 Mbyte Flash Memory 70, Data Cache 76, Program Cache 77

The ACP 31 contains a 4 Mbyte Flash memory 70 for storing the Artcamprogram.

As it is unlikely that the Flash memory 70 will be able to operate atthe 10 ns cycle time required by the CPU, a program cache 77 is providedto improve performance. The Program cache 77 is a read only cache.

The data used by CPU programs comes through the CPU Memory Decoder 68and if the address is in DRAM, through a general Data cache 76. Theseparation allows the CPU to operate independently of the VLIW VectorProcessor 74. If the data requirements are low for a given process, itcan consequently operate completely out of cache. Finally, the Programcache 77 can be read as data by the CPU rather than purely as programinstructions. This allows tables, microcode for the VLIW etc to beloaded from the Flash memory 70.

The data cache 76 is further provided to improve performance. Thisrequirement is mostly due to the use of a RAMbus DRAM, which can providehigh-speed data in bursts, but is inefficient for single byte accesses.The CPU has access to a memory caching system that allows flexiblemanipulation of CPU data cache 76 sizes.

The Data cache 76 handles all DRAM requests (reads and writes of data)from the CPU, the VLIW Vector Processor 74, and the Display Controller88. These requests may have very different profiles in terms of memoryusage and algorithmic timing requirements. For example, a VLIW processmay be processing an image in linear memory, and lookup a value in atable for each value in the image. There is little need to cache much ofthe image, but it may be desirable to cache the entire lookup table sothat no real memory access is required. Because of these differingrequirements, the Data cache 76 allows for an intelligent definition ofcaching.

A total of 8 buses 182 connect the VLIW Vector Processor 74 to the Datacache 76. Each bus is connected to an I/O Address Generator. (There are2 I/O Address Generators 189, 190 per Processing Unit 178, and there are4 Processing Units in the VLIW Vector Processor 74.

The Data cache 76 as described allows for the Display Controller 88 andVLIW Vector Processor 74 to be active simultaneously. If the operationof these two components were deemed to never occur simultaneously, atotal 9 Cache Groups would suffice. The CPU would use Cache Group 0, andthe VLIW Vector Processor 74 and the Display Controller 88 would sharethe remaining 8 Cache Groups, requiring only 3 bits (rather than 4) todefine which Cache Group would satisfy a particular request.

3. Direct RAMbus Interface 81

The DRAM used by the Artcam is a single channel 64 Mbit (8 MB) RAMbusRDRAM operating at 1.6 GB/sec. RDRAM accesses are by a single channel(16-bit data path) controller

Although the Rambus DRAM interface 81 is capable of very high-speedmemory access (an average throughput of 32 bytes in 25 ns), it is notefficient dealing with single byte requests. In order to reduceeffective memory latency, the ACP 31 contains 128 cache lines. Eachcache line is 32 bytes wide. Thus the total amount of data cache 76 is4096 bytes (4 KB).

The DRAM Interface 81 is responsible for interfacing between otherclient portions of the ACP chip and the RAMBUS DRAM. In effect, eachmodule within the DRAM Interface is an address generator.

4. JTAG Interface 85

A standard JTAG (Joint Test Action Group) Interface is included in theACP 31 for testing purposes. Due to the complexity of the chip, avariety of testing techniques are required, including BIST (Built InSelf Test) and functional block isolation. An overhead of 10% in chiparea is assumed for overall chip testing circuitry. The test circuitryis beyond the scope of this document.

5. Serial Interfaces 52, 64

The ACP includes a standard USB serial port 52, which is connected tothe internal chip low speed bus, thereby allowing the CPU to control it.Further included is a standard low-speed serial port, which is alsoconnected to the internal chip low speed bus, allowing the CPU tocontrol it. The standard low-speed serial port is designed to beoptionally connected to a keyboard to allow simple data input tocustomize prints. A further 2 standard low-speed serial ports connectedto the internal chip low speed bus are provided as authentication chipserial interfaces 64. 2 ports are provided to connect to both theon-camera Authentication chip, and to the print-roll Authentication chipusing separate lines. Only using I line may make it possible for a cloneprint-roll manufacturer to design a chip which, instead of generating anauthentication code, tricks the camera into using the code generated bythe authentication chip in the camera.

6. Parallel Interface 67

The parallel interface connects the ACP 31 to individual staticelectrical signals. The CPU is able to control each of these connectionsas memory-mapped I/O via the low speed bus.

7. VLIW Input and Output FIFOs 78, 79

The VLIW Input and Output FIFOs are 8 bit wide FIFOs used forcommunicating between processes and the VLIW Vector Processor 74. BothFIFOs are under the control of the VLIW Vector Processor 74, but can becleared and queried (e.g. for status) etc by the CPU.

A client writes 8-bit data to the VLIW Input FIFO 78 in order to havethe data processed by the VLIW Vector Processor 74. Clients include theImage Sensor Interface, Artcard Interface, and CPU. Each of theseprocesses is able to offload processing by simply writing the data tothe FIFO, and letting the VLIW Vector Processor 74 do all the hard work.An example of the use of a client's use of the VLIW Input FIFO 78 is theImage Sensor Interface (ISI 83). The ISI 83 takes data from the ImageSensor and writes it to the FIFO. A VLIW process takes it from the FIFO,transforming it into the correct image data format, and writing it outto DRAM. The ISI 83 becomes much simpler as a result.

The VLIW Vector Processor 74 writes 8-bit data to the VLIW Output FIFO79 where clients can read it. Clients include the Print Head Interfaceand the CPU. Both of these clients is able to offload processing bysimply reading the already processed data from the FIFO, and letting theVLIW Vector Processor 74 do all the hard work. The CPU can also beinterrupted whenever data is placed into the VLIW Output FIFO 79,allowing it to only process the data as it becomes available rather thanpolling the FIFO continuously. An example of the use of a client's useof the VLIW Output FIFO 79 is the Print Head Interface (PHI 62). A VLIWprocess takes an image, rotates it to the correct orientation, colorconverts it, and dithers the resulting image according to the print headrequirements. The PHI 62 reads the dithered formatted 8-bit data fromthe VLIW Output FIFO 79 and simply passes it on to the Print Headexternal to the ACP 31. The PHI 62 becomes much simpler as a result.

8. VLIW Vector Processor 74

To achieve the high processing requirements of Artcam, the ACP 31contains a VLIW (Very Long Instruction Word) Vector Processor. The VLIWprocessor is a set of 4 identical Processing Units (PU e.g 178) workingin parallel, connected by a crossbar switch 183. Each PU e.g 178 canperform four 8-bit multiplications, eight 8-bit additions, three 32-bitadditions, I/O processing, and various logical operations in each cycle.The PUs e.g 178 are microcoded, and each has two Address Generators 189,190 to allow full use of available cycles for data processing. The fourPUs e.g 178 are normally synchronized to provide a tightly interactingVLIW processor. Clocking at 200 MHz, the VLIW Vector Processor 74 runsat 12 Gops (12 billion operations per second). Instructions are tunedfor image processing functions such as warping, artistic brushing,complex synthetic illumination, color transforms, image filtering, andcompositing. These are accelerated by two orders of magnitude overdesktop computers.

As shown in more detail in FIG. 3( a), the VLIW Vector Processor 74 is 4PUs e.g 178 connected by a crossbar switch 183 such that each PU e.g 178provides two inputs to, and takes two outputs from, the crossbar switch183. Two common registers form a control and synchronization mechanismfor the PUs e.g 178. 8 Cache buses 182 allow connectivity to DRAM viathe Data cache 76, with 2 buses going to each PU e.g 178 (1 bus per I/OAddress Generator).

Each PU e.g 178 consists of an ALU 188 (containing a number of registers& some arithmetic logic for processing data), some microcode RAM 196,and connections to the outside world (including other ALUs). A local PUstate machine runs in microcode and is the means by which the PU e.g 178is controlled. Each PU e.g 178 contains two I/O Address Generators 189,190 controlling data flow between DRAM (via the Data cache 76) and theALU 188 (via Input FIFO and Output FIFO). The address generator is ableto read and write data (specifically images in a variety of formats) aswell as tables and simulated FIFOs in DRAM. The formats are customizableunder software control, but are not microcoded. Data taken from the Datacache 76 is transferred to the ALU 188 via the 16-bit wide Input FIFO.Output data is written to the 16-bit wide Output FIFO and from there tothe Data cache 76. Finally, all PUs e.g 178 share a single 8-bit wideVLIW Input FIFO 78 and a single 8-bit wide VLIW Output FIFO 79. The lowspeed data bus connection allows the CPU to read and write registers inthe PU e.g 178, update microcode, as well as the common registers sharedby all PUs e.g 178 in the VLIW Vector Processor 74.

PUs e.g 178 share data with each other directly via the externalcrossbar. They also transfer data to and from external processes as wellas DRAM. Each PU e.g 178 has 2 I/O Address Generators 189, 190 fortransferring data to and from DRAM. A PU e.g 178 can send data to DRAMvia an I/O Address Generator's Output FIFO e.g. 186, or accept data fromDRAM via an I/O Address Generator's Input FIFO 187.

9. CMOS Image Sensor Interface (ISI 83)

The CMOS Image Sensor Interface (ISI 83) takes data from the CMOS ImageSensor and makes it available for storage in DRAM. The image sensor hasan aspect ratio of 3:2, with a typical resolution of 750×500 samples,yielding 375K (8 bits per pixel). Each 2×2 pixel block has theconfiguration as shown in FIG. 4. The ISI 83 is a state machine thatsends control information to the Image Sensor, including frame syncpulses and pixel clock pulses in order to read the image. Pixels areread from the image sensor and placed into the VLIW Input FIFO 78. TheVLIW is then able to process and/or store the pixels. This isillustrated further in FIG. 5. The ISI 83 is used in conjunction with aVLIW program that stores the sensed Photo Image in DRAM. Processingoccurs in 2 steps:

-   -   A small VLIW program reads the pixels from the FIFO and writes        them to DRAM via a Sequential Write Iterator.    -   The Photo Image in DRAM is rotated 90, 180 or 270 degrees        according to the orientation of the camera when the photo was        taken.

If the rotation is 0 degrees, then step 1 merely writes the Photo Imageout to the final Photo Image location and step 2 is not performed. Ifthe rotation is other than 0 degrees, the image is written out to atemporary area (for example into the Print Image memory area), and thenrotated during step 2 into the final Photo Image location.

The orientation is important for converting between the sensed PhotoImage and the internal format image, since the relative positioning ofR, G, and B pixels changes with orientation. The processed image mayalso have to be rotated during the Print process in order to be in thecorrect orientation for printing. The 3D model of the Artcam has 2 imagesensors, with their inputs multiplexed to a single ISI 83 (differentmicrocode, but same ACP 31). Since each sensor is a frame store, bothimages can be taken simultaneously, and then transferred to memory oneat a time.

10. Color TFT LCD Interface/Display Controller 88

The Display Controller (Color TFT LCD Interface) 88 is used in thoseArtcam models that incorporate a flat panel display. An example displayis a TFT LCD of resolution 240×160 pixels. The structure of the DisplayController 88 is illustrated in FIG. 6. The Display Controller 88 StateMachine contains registers that control the timing of the SyncGeneration, where the display image is to be taken from (in DRAM via theData cache 76 via a specific Cache Group), and whether the TFT should beactive or not (via TFT Enable) at the moment. The CPU can write to theseregisters via the low speed bus.

11. Artcard Interface 87

The Artcard Interface (AI) 87 takes data from the linear image Sensorwhile an Artcard is passing under it, and makes that data available forstorage in DRAM. The AI 87 is a state machine that sends controlinformation to the linear sensor, including LineSync pulses andPixelClock pulses in order to read the image. Pixels are read from thelinear sensor and placed into the VLIW Input FIFO 78. The VLIW is thenable to process and/or store the pixels.

The Artcard Interface (AI) 87 is responsible for taking an Artcard imagefrom the Artcard Reader 34, and decoding it into the original data(usually a Vark script). Specifically, the AI 87 accepts signals fromthe Artcard scanner linear CCD 34, detects the bit pattern printed onthe card, and converts the bit pattern into the original data,correcting read errors.

With no Artcard 9 inserted, the image printed from an Artcam is simplythe sensed Photo Image cleaned up by any standard image processingroutines. The Artcard 9 is the means by which users are able to modify aphoto before printing it out. By the simple task of inserting a specificArtcard 9 into an Artcam, a user is able to define complex imageprocessing to be performed on the Photo Image.

With no Artcard inserted the Photo Image is processed in a standard wayto create the Print Image. When a single Artcard 9 is inserted into theArtcam, that Artcard's effect is applied to the Photo Image to generatethe Print Image.

When the Artcard 9 is removed (ejected), the printed image reverts tothe Photo Image processed in a standard way. When the user presses thebutton to eject an Artcard, an event is placed in the event queuemaintained by the operating system running on the Artcam CentralProcessor 31. When the event is processed (for example after the currentPrint has occurred), the following things occur:

If the current Artcard is valid, then the Print Image is marked asinvalid and a ‘Process Standard’ event is placed in the event queue.When the event is eventually processed it will perform the standardimage processing operations on the Photo Image to produce the PrintImage.

The motor is started to eject the Artcard and a time-specific‘Stop-Motor’ Event is added to the event queue.

When a user inserts an Artcard 9, the Artcard Sensor 49 detects itnotifying the ACP72. This results in the software inserting an ‘ArtcardInserted’ event into the event queue. When the event is processedseveral things occur:

-   -   The current Artcard is marked as invalid (as opposed to ‘none’).    -   The Print Image is marked as invalid.    -   The Artcard motor 37 is started up to load the Artcard    -   The Artcard Interface 87 is instructed to read the Artcard    -   The Artcard Interface 87 accepts signals from the Artcard        scanner linear CCD 34, detects the bit pattern printed on the        card, and corrects errors in the detected bit pattern, producing        a valid Artcard data block in DRAM.

As illustrated in FIG. 8, the Data Card reading process has 4 phasesoperated while the pixel data is read from the card. The phases are asfollows:

-   -   Phase 1—Detect data area on Artcard    -   Phase 2—Detect bit pattern from Artcard based on CCD pixels, and        write as bytes.    -   Phase 3—Descramble and XOR the byte-pattern    -   Phase 4—Decode data (Reed-Solomon decode)

As illustrated in FIG. 9, the Artcard 9 must be sampled at least atdouble the printed resolution to satisfy Nyquist's Theorem. In practiceit is better to sample at a higher rate than this. Preferably, thepixels are sampled 230 at 3 times the resolution of a printed dot ineach dimension, requiring 9 pixels to define a single dot. Thus if theresolution of the Artcard 9 is 1600 dpi, and the resolution of thesensor 34 is 4800 dpi, then using a 50 mm CCD image sensor results in9450 pixels per column. Therefore if we require 2 MB of dot data (at 9pixels per dot) then this requires 2 MB*8*9/9450=15,978columns=approximately 16,000 columns. Of course if a dot is not exactlyaligned with the sampling CCD the worst and most likely case is that adot will be sensed over a 16 pixel area (4×4) 231.

An Artcard 9 may be slightly warped due to heat damage, slightly rotated(up to, say 1 degree) due to differences in insertion into an Artcardreader, and can have slight differences in true data rate due tofluctuations in the speed of the reader motor 37. These changes willcause columns of data from the card not to be read as correspondingcolumns of pixel data. As illustrated in FIG. 10, a 1 degree rotation inthe Artcard 9 can cause the pixels from a column on the card to be readas pixels across 166 columns.

When an Artcard 9 is inserted, the old stored Print Image and anyexpanded Photo Image becomes invalid. The new Artcard 9 can containdirections for creating a new image based on the currently capturedPhoto Image. The old Print Image is invalid, and the area holdingexpanded Photo Image data and image pyramid is invalid, leaving morethan 5 MB that can be used as scratch memory during the read process.Strictly speaking, the 1 MB area where the Artcard raw data is to bewritten can also be used as scratch data during the Artcard read processas long as by the time the final Reed-Solomon decode is to occur, that 1MB area is free again. The reading process described here does not makeuse of the extra 1 MB area (except as a final destination for the data).

Turning now to FIG. 11, there is shown a flowchart 220 of the stepsnecessary to decode the Artcard data. These steps include reading in theArtcard 221, and decoding the read data to produce corresponding encodedXORed scrambled bitmap data 223. Next a checkerboard XOR is applied tothe data to produces encoded scrambled data 224. This data is thenunscrambled 227 to produce data 225 before this data is subjected toReed-Solomon decoding to produce the original raw data 226.Alternatively, unscrambling and XOR process can take place together, notrequiring a separate pass of the data.

Phase 1

As the Artcard 9 moves past the CCD 34 the AI must detect the start ofthe data area by robustly detecting special targets on the Artcard tothe left of the data area. If these cannot be detected, the card ismarked as invalid. The detection must occur in real-time, while theArtcard 9 is moving past the CCD 34.

If necessary, rotation invariance can be provided. In this case, thetargets are repeated on the right side of the Artcard, but relative tothe bottom right corner instead of the top corner. In this way thetargets end up in the correct orientation if the card is inserted the“wrong” way. Phase 3 below can be altered to detect the orientation ofthe data, and account for the potential rotation.

Phase 2

Once the data area has been determined, the main read process begins,placing pixel data from the CCD into an ‘Artcard data window’, detectingbits from this window, assembling the detected bits into bytes, andconstructing a byte-image in DRAM. This must all be done while theArtcard is moving past the CCD.

Phase 3

Once all the pixels have been read from the Artcard data area, theArtcard motor 37 can be stopped, and the byte image descrambled andXORed. Although not requiring real-time performance, the process shouldbe fast enough not to annoy the human operator. The process must take 2MB of scrambled bit-image and write the unscrambled/XORed bit-image to aseparate 2 MB image.

Phase 4

The final phase in the Artcard read process is the Reed-Solomon decodingprocess, where the 2 MB bit-image is decoded into a 1 MB valid Artcarddata area. Again, while not requiring real-time performance it is stillnecessary to decode quickly with regard to the human operator. If thedecode process is valid, the card is marked as valid. If the decodefailed, any duplicates of data in the bit-image are attempted to bedecoded, a process that is repeated until success or until there are nomore duplicate images of the data in the bit image.

A Detailed Description of Each of the Four Phases Follows: A. Phase 1

A(i). Detect Data Area on Artcard

This phase is concerned with robustly detecting the left-hand side ofthe data area on the Artcard 9. Accurate detection of the data area isachieved by accurate detection of special targets printed on the leftside of the card. These targets are especially designed to be easy todetect even if rotated up to 1 degree.

Turning to FIG. 12, there is shown an enlargement of the left hand sideof an Artcard 9. The side of the card is divided into 16 bands, 239 witha target eg. 241 located at the center of each band. The bands arelogical in that there is no line drawn to separate bands. Turning toFIG. 13, there is shown a single target 241. The target 241, is aprinted black square containing a single white dot. The idea is todetect firstly as many targets 241 as possible, and then to join atleast 8 of the detected white-dot locations into a single logicalstraight line. If this can be done, the start of the data area 243 is afixed distance from this logical line. If it cannot be done, then thecard is rejected as invalid.

As shown in FIG. 12, the height of the card 9 is 3150 dots. A target(Target0) 241 is placed a fixed distance of 24 dots away from the topleft corner 244 of the data area so that it falls well within the firstof 16 equal sized regions 239 of 192 dots (576 pixels) with no target inthe final pixel region of the card. The target 241 must be big enough tobe easy to detect, yet be small enough not to go outside the height ofthe region if the card is rotated 1 degree. A suitable size for thetarget is a 31×31 dot (93×93 sensed pixels) black square 241 with thewhite dot 242.

At the worst rotation of 1 degree, a 1 column shift occurs every 57pixels. Therefore in a 590 pixel sized band, we cannot place any part ofour symbol in the top or bottom 12 pixels or so of the band or theycould be detected in the wrong band at CCD read time if the card isworst case rotated.

Therefore, if the black part of the rectangle is 57 pixels high (19dots) we can be sure that at least 9.5 black pixels will be read in thesame column by the CCD (worst case is half the pixels are in one columnand half in the next). To be sure of reading at least 10 black dots inthe same column, we must have a height of 20 dots. To give room forerroneous detection on the edge of the start of the black dots, weincrease the number of dots to 31, giving us 15 on either side of thewhite dot at the target's local coordinate (15, 15). 31 dots is 91pixels, which at most suffers a 3 pixel shift in column, easily withinthe 576 pixel band.

Thus each target is a block of 31×31 dots (93×93 pixels) each with thecomposition:

-   -   15 columns of 31 black dots each (45 pixel width columns of 93        pixels).    -   1 column of 15 black dots (45 pixels) followed by 1 white dot (3        pixels) and then a further 15 black dots (45 pixels)    -   15 columns of 31 black dots each (45 pixel width columns of 93        pixels)

A(ii). Detect Targets

Targets are detected by reading columns of pixels, one column at a timerather than by detecting dots. It is necessary to look within a givenband for a number of columns consisting of large numbers of contiguousblack pixels to build up the left side of a target. Next, it is expectedto see a white region in the center of further black columns, andfinally the black columns to the left of the target center.

Eight cache lines are required for good cache performance on the readingof the pixels. Each logical read fills 4 cache lines via 4 sub-readswhile the other 4 cache-lines are being used. This effectively uses up13% of the available DRAM bandwidth.

As illustrated in FIG. 14, the detection mechanism FIFO for detectingthe targets uses a filter 245, run-length encoder 246, and a FIFO 247that requires special wiring of the top 3 elements (S1, S2, and S3) forrandom access.

The columns of input pixels are processed one at a time until either allthe targets are found, or until a specified number of columns have beenprocessed. To process a column, the pixels are read from DRAM, passedthrough a filter 245 to detect a 0 or 1, and then run length encoded246. The bit value and the number of contiguous bits of the same valueare placed in FIFO 247. Each entry of the FIFO 249 is in 8 bits, 7 bits250 to hold the run-length, and 1 bit 249 to hold the value of the bitdetected.

The run-length encoder 246 only encodes contiguous pixels within a 576pixel (192 dot) region.

When beginning to process a given pixel column, the register valueS2StartPixel 254 is reset to 0. As entries in the FIFO advance from S2to S1, they are also added 255 to the existing S2StartPixel value,giving the exact pixel position of the run currently defined in S2.Looking at each of the 3 cases of interest in the FIFO, S2StartPixel canbe used to determine the start of the black area of a target (Cases 1and 2), and also the start of the white dot in the center of the target(Case 3).

At the end of processing a given column, a comparison is made of thecurrent column to the maximum number of columns for target detection. Ifthe number of columns allowed has been exceeded, then it is necessary tocheck how many targets have been found. If fewer than 8 have been found,the card is considered invalid.

A(iii). Process Targets

After the targets have been detected, they should be processed. All thetargets may be available or merely some of them. Some targets may alsohave been erroneously detected.

This phase of processing is to determine a mathematical line that passesthrough the center of as many targets as possible. The more targets thatthe line passes through, the more confident the target position has beenfound. The limit is set to be 8 targets. If a line passes through atleast 8 targets, then it is taken to be the right one.

It is all right to take a brute-force but straightforward approach sincethere is the time to do so (see below), and lowering complexity makestesting easier. It is necessary to determine the line between targets 0and 1 (if both targets are considered valid) and then determine how manytargets fall on this line. Then we determine the line between targets 0and 2, and repeat the process. Eventually we do the same for the linebetween targets 1 and 2, 1 and 3 etc. and finally for the line betweentargets 14 and 15. Assuming all the targets have been found, we need toperform 15+14+13+ . . . =90 sets of calculations (with each set ofcalculations requiring 16 tests=1440 actual calculations), and choosethe line which has the maximum number of targets found along the line.

As illustrated in FIG. 8, to determine a CurrentLine 260 from Target A261 and target B, it is necessary to calculate Δrow (264) & Δcolumn(263) between targets 261, 262, and the location of Target A. It is thenpossible to move from Target 0 to Target 1 etc. by adding Δrow andΔcolumn. The found (if actually found) location of target N can becompared to the calculated expected position of Target N on the line,and if it falls within the tolerance, then Target N is determined to beon the line.

To move from one expected target to the next (e.g. from Target0 toTarget1), we simply add Δrow and Δcolumn to row and column respectively.To check if each target is on the line, we must calculate the expectedposition of Target0, and then perform one add and one comparison foreach target ordinate.

At the end of comparing all 16 targets against a maximum of 90 lines,the result is the best line through the valid targets. If that linepasses through at least 8 targets (i.e. MaxFound >=8), it can be saidthat enough targets have been found to form a line, and thus the cardcan be processed. If the best line passes through fewer than 8, then thecard is considered invalid.

The resulting algorithm takes 180 divides to calculate Δrow and Δcolumn,180 multiply/adds to calculate target0 position, and then 2880adds/comparisons. The time we have to perform this processing is thetime taken to read 36 columns of pixel data=3,374,892 ns. Not evenaccounting for the fact that an add takes less time than a divide, it isnecessary to perform 3240 mathematical operations in 3,374,892 ns. Thatgives approximately 1040 ns per operation, or 104 cycles. The CPU cantherefore safely perform the entire processing of targets, reducingcomplexity of design.

A(iv). Update Centroids Based on Data Edge Border and Clockmarks

Step 0: Locate the Data Area

From Target 0 (241 of FIG. 12) it is a predetermined fixed distance inrows and columns to the top left border 244 of the data area, and then afurther 1 dot column to the vertical clock marks 276. So we use TargetA,Δrow and Δcolumn found in the previous stage (Δrow and Δcolumn refer todistances between targets) to calculate the centroid or expectedlocation for Target0 as described previously.

Since the fixed pixel offset from Target0 to the data area is related tothe distance between targets (192 dots between targets, and 24 dotsbetween Target0 and the data area 243), simply add Δrow/8 to Target0'scentroid column coordinate (aspect ratio of dots is 1:1). Thus the topco-ordinate can be defined as:

(column_(DotColumnTop)=column_(Target0)+(Δrow/8)

(row_(DotColumnTop)=row_(Target0)+(Δcolumn/8)

Next Δrow and Δcolumn are updated to give the number of pixels betweendots in a single column (instead of between targets) by dividing them bythe number of dots between targets:

Δrow=Δrow/192

Δcolumn=Δcolumn/192

We also set the currentColumn register (see Phase 2) to be −1 so thatafter step 2, when phase 2 begins, the currentColumn register willincrement from −1 to 0.

Step 1: Write Out the Initial Centroid Deltas (Δ) and Bit History

This involves writing setup information required for Phase 2. This canbe achieved by writing 0s to all the Δrow and Δcolumn entries for eachrow, and a bit history. The bit history is actually an expected bithistory since it is known that to the left of the clock mark column 276is a border column 277, and before that, a white area. The bit historytherefore is 011, 010, 011, 010 etc.

Step 2: Update the Centroids Based on Actual Pixels Read.

The bit history is set up in Step 1 according to the expected clockmarks and data border. The actual centroids for each dot row can now bemore accurately set (they were initially 0) by comparing the expecteddata against the actual pixel values. The centroid updating mechanism isachieved by simply performing step 3 of Phase 2.

B. Phase 2

B(i). Detect Bit Pattern from Artcard Based on Pixels Read, and Write asBytes.

Since a dot from the Artcard 9 requires a minimum of 9 sensed pixelsover 3 columns to be represented, there is little point in performingdot detection calculations every sensed pixel column. It is better toaverage the time required for processing over the average dotoccurrence, and thus make the most of the available processing time.This allows processing of a column of dots from an Artcard 9 in the timeit takes to read 3 columns of data from the Artcard. Although the mostlikely case is that it takes 4 columns to represent a dot, the 4^(th)column will be the last column of one dot and the first column of a nextdot. Processing should therefore be limited to only 3 columns.

As the pixels from the CCD are written to the DRAM in 13% of the timeavailable, 83% of the time is available for processing of 1 column ofdots i.e. 83% of (93,747*3)=83% of 281,241 ns=233,430 ns.

In the available time, it is necessary to detect 3150 dots, and writetheir bit values into the raw data area of memory. The processingtherefore requires the following steps:

-   -   For each column of dots on the Artcard:        -   Step 0: Advance to the next dot column        -   Step 1: Detect the top and bottom of an Artcard dot column            (check clock marks)        -   Step 2: Process the dot column, detecting bits and storing            them appropriately        -   Step 3: Update the centroids

Since we are processing the Artcard's logical dot columns, and these mayshift over 165 pixels, the worst case is that we cannot process thefirst column until at least 165 columns have been read into DRAM. Phase2 would therefore finish the same amount of time after the read processhad terminated. The worst case time is: 165*93,747 ns=15,468,255 ns or0.015 seconds.

Step 0: Advance to the Next Dot Column

In order to advance to the next column of dots we add Δrow and Δcolumnto the dotColumnTop to give us the centroid of the dot at the top of thecolumn. The first time we do this, we are currently at the clock markscolumn 276 to the left of the bit image data area, and so we advance tothe first column of data. Since Δrow and Δcolumn refer to distancebetween dots within a column, to move between dot columns it isnecessary to add Δrow to column_(dotColumnTop) and Δcolumn torow_(dotColumnTop).

To keep track of what column number is being processed, the columnnumber is recorded in a register called CurrentColumn. Every time thesensor advances to the next dot column it is necessary to increment theCurrentColumn register. The first time it is incremented, it isincremented from −1 to 0 (see Step 0 Phase 1). The CurrentColumnregister determines when to terminate the read process (when reachingmaxColumns), and also is used to advance the DataOut Pointer to the nextcolumn of byte information once all 8 bits have been written to the byte(once every 8 dot columns). The lower 3 bits determine what bit we're upto within the current byte. It will be the same bit being written forthe whole column.

Step 1: Detect the Top and Bottom of an Artcard Dot Column.

In order to process a dot column from an Artcard, it is necessary todetect the top and bottom of a column. The column should form a straightline between the top and bottom of the column (except for local warpingetc.). Initially dotColumnTop points to the clock mark column 276. Wesimply toggle the expected value, write it out into the bit history, andmove on to step 2, whose first task will be to add the Δrow and Δcolumnvalues to dotColumnTop to arrive at the first data dot of the column.

Step 2: Process an Artcard's Dot Column

Given the centroids of the top and bottom of a column in pixelcoordinates the column should form a straight line between them, withpossible minor variances due to warping etc.

Assuming the processing is to start at the top of a column (at the topcentroid coordinate) and move down to the bottom of the column,subsequent expected dot centroids are given as:

row_(next)=row+Δrow

column_(next)=column+Δcolumn

This gives us the address of the expected centroid for the next dot ofthe column. However to account for local warping and error we addanother Δrow and Δcolumn based on the last time we found the dot in agiven row. In this way we can account for small drifts that accumulateinto a maximum drift of some percentage from the straight line joiningthe top of the column to the bottom.

We therefore keep 2 values for each row, but store them in separatetables since the row history is used in step 3 of this phase.

-   -   Δrow and Δcolumn (2@4 bits each=1 byte)    -   row history (3 bits per row, 2 rows are stored per byte)

For each row we need to read a Δrow and Δcolumn to determine the changeto the centroid. The read process takes 5% of the bandwidth and 2 cachelines:

76*(3150/32)+2*3150=13,824 ns=5% of bandwidth

Once the centroid has been determined, the pixels around the centroidneed to be examined to detect the status of the dot and hence the valueof the bit. In the worst case a dot covers a 4×4 pixel area. However,thanks to the fact that we are sampling at 3 times the resolution of thedot, the number of pixels required to detect the status of the dot andhence the bit value is much less than this. We only require access to 3columns of pixel columns at any one time.

In the worst case of pixel drift due to a 1% rotation, centroids willshift 1 column every 57 pixel rows, but since a dot is 3 pixels indiameter, a given column will be valid for 171 pixel rows (3*57). As abyte contains 2 pixels, the number of bytes valid in each buffered read(4 cache lines) will be a worst case of 86 (out of 128 read).

Once the bit has been detected it must be written out to DRAM. We storethe bits from 8 columns as a set of contiguous bytes to minimize DRAMdelay. Since all the bits from a given dot column will correspond to thenext bit position in a data byte, we can read the old value for thebyte, shift and OR in the new bit, and write the byte back. Theread/shift&OR/write process requires 2 cache lines.

We need to read and write the bit history for the given row as we updateit. We only require 3 bits of history per row, allowing the storage of 2rows of history in a single byte. The read/shift&OR/write processrequires 2 cache lines.

B(ii). Detecting a Dot

The process of detecting the value of a dot (and hence the value of abit) given a centroid is accomplished by examining 3 pixel values andgetting the result from a lookup table. The process is fairly simple andis illustrated in FIG. 15. A dot 290 has a radius of about 1.5 pixels.Therefore the pixel 291 that holds the centroid, regardless of theactual position of the centroid within that pixel, should be 100% of thedot's value. If the centroid is exactly in the center of the pixel 291,then the pixels above 292 & below 293 the centroid's pixel, as well asthe pixels to the left 294 & right 295 of the centroid's pixel willcontain a majority of the dot's value. The further a centroid is awayfrom the exact center of the pixel 295, the more likely that more thanthe center pixel will have 100% coverage by the dot.

Although FIG. 15 only shows centroids differing to the left and belowthe center, the same relationship obviously holds for centroids aboveand to the right of center. In Case 1, the centroid is exactly in thecenter of the middle pixel 295. The center pixel 295 is completelycovered by the dot, and the pixels above, below, left, and right arealso well covered by the dot. In Case 2, the centroid is to the left ofthe center of the middle pixel 291. The center pixel is still completelycovered by the dot, and the pixel 294 to the left of the center is nowcompletely covered by the dot. The pixels above 292 and below 293 arestill well covered. In Case 3, the centroid is below the center of themiddle pixel 291. The center pixel 291 is still completely covered bythe dot 291, and the pixel below center is now completely covered by thedot. The pixels left 294 and right 295 of center are still well covered.In Case 4, the centroid is left and below the center of the middlepixel. The center pixel 291 is still completely covered by the dot, andboth the pixel to the left of center 294 and the pixel below center 293are completely covered by the dot.

The algorithm for updating the centroid uses the distance of thecentroid from the center of the middle pixel 291 in order to select 3representative pixels and thus decide the value of the dot:

-   -   Pixel 1: the pixel containing the centroid    -   Pixel 2: the pixel to the left of Pixel 1 if the centroid's X        coordinate (column value) is <½, otherwise the pixel to the        right of Pixel 1.    -   Pixel 3: the pixel above pixel 1 if the centroid's Y coordinate        (row value) is <½, otherwise the pixel below Pixel 1.

As shown in FIG. 16, the value of each pixel is output to apre-calculated lookup table 301. The 3 pixels are fed into a 12-bitlookup table, which outputs a single bit indicating the value of thedot—on or off. The lookup table 301 is constructed at chip definitiontime, and can be compiled into about 500 gates. The lookup table can bea simple threshold table, with the exception that the center pixel(Pixel 1) is weighted more heavily.

Step 3: Update the Centroid Δs for Each Row in the Column

The idea of the Δs processing is to use the previous bit history togenerate a ‘perfect’ dot at the expected centroid location for each rowin a current column. The actual pixels (from the CCD) are compared withthe expected ‘perfect’ pixels. If the two match, then the actualcentroid location must be exactly in the expected position, so thecentroid Δs must be valid and not need updating. Otherwise a process ofchanging the centroid Δs needs to occur in order to best fit theexpected centroid location to the actual data. The new centroid Δs willbe used for processing the dot in the next column.

Updating the centroid Δs is done as a subsequent process from Step 2 forthe following reasons:

-   -   to reduce complexity in design, so that it can be performed as        Step 2 of Phase 1 there is enough bandwidth remaining to allow        it to allow reuse of DRAM buffers, and    -   to ensure that all the data required for centroid updating is        available at the start of the process without special        pipelining.

The centroid Δ are processed as Δcolumn Δrow respectively to reducecomplexity.

Although a given dot is 3 pixels in diameter, it is likely to occur in a4×4 pixel area. However the edge of one dot will as a result be in thesame pixel as the edge of the next dot. For this reason, centroidupdating requires more than simply the information about a given singledot.

FIG. 17 shows a single dot 310 from the previous column with a givencentroid 311. In this example, the dot 310 extend Δ over 4 pixel columns312-315 and in fact, part of the previous dot column's dot(coordinate=(Prevcolumn, Current Row)) has entered the current columnfor the dot on the current row. If the dot in the current row and columnwas white, we would expect the rightmost pixel column 314 from theprevious dot column to be a low value, since there is only the dotinformation from the previous column's dot (the current column's dot iswhite). From this we can see that the higher the pixel value is in thispixel column 315, the more the centroid should be to the right Ofcourse, if the dot to the right was also black, we cannot adjust thecentroid as we cannot get information sub-pixel. The same can be saidfor the dots to the left, above and below the dot at dot coordinates(PrevColumn, CurrentRow).

From this we can say that a maximum of 5 pixel columns and rows arerequired. It is possible to simplify the situation by taking the casesof row and column centroid Δs separately, treating them as the sameproblem, only rotated 90 degrees.

Taking the horizontal case first, it is necessary to change the columncentroid Δs if the expected pixels don't match the detected pixels. Fromthe bit history, the value of the bits found for the Current Row in thecurrent dot column, the previous dot column, and the (previous-1)th dotcolumn are known. The expected centroid location is also known. Usingthese two pieces of information, it is possible to generate a 20 bitexpected bit pattern should the read be ‘perfect’. The 20 bitbit-pattern represents the expected A values for each of the 5 pixelsacross the horizontal dimension. The first nibble would represent therightmost pixel of the leftmost dot. The next 3 nibbles represent the 3pixels across the center of the dot 310 from the previous column, andthe last nibble would be the leftmost pixel 317 of the rightmost dot(from the current column).

If the expected centroid is in the center of the pixel, we would expecta 20 bit pattern based on the following table:

Bit history Expected pixels 000 00000 001 0000D 010 0DFD0 011 0DFDD 100D0000 101 D000D 110 DDFD0 111 DDFDD

The pixels to the left and right of the center dot are either 0 or Ddepending on whether the bit was a 0 or 1 respectively. The center threepixels are either 000 or DFD depending on whether the bit was a 0 or 1respectively. These values are based on the physical area taken by a dotfor a given pixel. Depending on the distance of the centroid from theexact center of the pixel, we would expect data shifted slightly, whichreally only affects the pixels either side of the center pixel. Sincethere are 16 possibilities, it is possible to divide the distance fromthe center by 16 and use that amount to shift the expected pixels.

Once the 20 bit 5 pixel expected value has been determined it can becompared against the actual pixels read. This can proceed by subtractingthe expected pixels from the actual pixels read on a pixel by pixelbasis, and finally adding the differences together to obtain a distancefrom the expected A values.

FIG. 18 illustrates one form of implementation of the above algorithmwhich includes a look up table 320 which receives the bit history 322and central fractional component 323 and outputs 324 the corresponding20 bit number which is subtracted 321 from the central pixel input 326to produce a pixel difference 327.

This process is carried out for the expected centroid and once for ashift of the centroid left and right by 1 amount in Δcolumn. Thecentroid with the smallest difference from the actual pixels isconsidered to be the ‘winner’ and the Δcolumn updated accordingly (whichhopefully is ‘no change’). As a result, a Δcolumn cannot change by morethan 1 each dot column.

The process is repeated for the vertical pixels, and Δrow isconsequentially updated.

There is a large amount of scope here for parallelism. Depending on therate of the clock chosen for the ACP unit 31 these units can be placedin series (and thus the testing of 3 different Δ could occur inconsecutive clock cycles), or in parallel where all 3 can be testedsimultaneously. If the clock rate is fast enough, there is less need forparallelism.

C. Phase 3

C(i). Unscramble and XOR the Raw Data

Returning to FIG. 11, the next step in decoding is to unscramble and XORthe raw data. The 2 MB byte image, as taken from the Artcard, is in ascrambled XORed form. It must be unscrambled and re-XORed to retrievethe bit image necessary for the Reed Solomon decoder in phase 4.

Turning to FIG. 19, the unscrambling process 330 takes a 2 MB scrambledbyte image 331 and writes an unscrambled 2 MB image 332. The processcannot reasonably be performed in-place, so 2 sets of 2 MB areas areutilised. The scrambled data 331 is in symbol block order arranged in a16×16 array, with symbol block 0 (334) having all the symbol 0's fromall the code words in random order. Symbol block 1 has all the symbol1's from all the code words in random order etc. Since there are only255 symbols, the 256^(th) symbol block is currently unused.

A linear feedback shift register is used to determine the relationshipbetween the position within a symbol block eg. 334 and what code wordeg. 355 it came from. This works as long as the same seed is used whengenerating the original Artcard images. The XOR of bytes fromalternative source lines with 0xAA and 0x55 respectively is effectivelyfree (in time) since the bottleneck of time is waiting for the DRAM tobe ready to read/write to non-sequential addresses.

The timing of the unscrambling XOR process is effectively 2 MB of randombyte-reads, and 2 MB of random byte-writes i.e. 2*(2 MB*76 ns+2 MB*2ns)=327,155,712 ns or approximately 0.33 seconds. This timing assumes nocaching.

D. Phase 4

D(i). Reed Solomon Decode

This phase is a loop, iterating through copies of the data in the bitimage, passing them to the Reed-Solomon decode module until either asuccessful decode is made or until there are no more copies to attemptdecode from.

The Reed-Solomon decoder used can be the VLIW processor, suitablyprogrammed or, alternatively, a separate hardwired core such as LSILogic's L64712. The L64712 has a throughput of 50 Mbits per second(around 6.25 MB per second), so the time may be bound by the speed ofthe Reed-Solomon decoder rather than the 2 MB read and 1 MB write memoryaccess time (500 MB/sec for sequential accesses). The time taken in theworst case is thus 2/6.25s=approximately 0.32 seconds.

The overall time taken to read the Artcard 9 and decode it is thereforeapproximately 2.15 seconds. The apparent delay to the user is actuallyonly 0.65 seconds (the total of Phases 3 and 4), since the Artcard stopsmoving after 1.5 seconds.

Once the Artcard is loaded, the Artvark script must be interpreted,Rather than run the script immediately, the script is only run upon thepressing of the ‘Print’ button 13 (FIG. 1). The taken to run the scriptwill vary depending on the complexity of the script, and must be takeninto account for the perceived delay between pressing the print buttonand the actual print button and the actual printing.

III. VLIW Processor 74

As noted previously, the VLIW processor 74 is a digital processingsystem that accelerates computationally expensive Vark functions. Thebalance of functions performed in software by the CPU core 72, and inhardware by the VLIW processor 74 will be implementation dependent. Thegoal of the VLIW processor 74 is to assist all Artcard styles to executein a time that does not seem too slow to the user. As CPUs become fasterand more powerful, the number of functions requiring hardwareacceleration becomes less and less.

IV. Print Head

FIG. 22 illustrates the logical layout of a single print Head whichlogically consists of 8 segments, each printing bi-level cyan, magenta,and yellow onto a portion of the page. Each segment prints 750 dots ofone color, 375 even dots on one row, and 375 odd dots on another.

Each dot is represented in the Print Head segment by a single bit. Thedata must be loaded 1 bit at a time by placing the data on the segment'sBitValue pin, and clocked in to a shift register in the segmentaccording to a BitClock. Since the data is loaded into a shift register,the order of loading bits must be correct. Data can be clocked in to thePrint Head at a maximum rate of 10 MHz.

Once all the bits have been loaded, they must be transferred in parallelto the Print Head output buffer, ready for printing. The transfer isaccomplished by a single pulse on the segment's ParallelXferClock pin.

In order to conserve power, not all the dots of the Print Head have tobe printed simultaneously. A set of control lines enables the printingof specific dots. An external controller, such as the ACP, can changethe number of dots printed at once, as well as the duration of the printpulse in accordance with speed and/or power requirements.

The Print Head Interface 62 connects the ACP to the Print Head,providing both data and appropriate signals to the external Print Head.The Print Head Interface 62 works in conjunction with both a VLIWprocessor 74 and a software algorithm running on the CPU in order toprint a photo in approximately 2 seconds.

There are 2 phases that must occur before an image is in the hand of theArtcam user:

-   -   1. Preparation of the image to be printed    -   2. Printing the prepared image

Preparation of an image only needs to be performed once. Printing theimage can be performed as many times as desired.

Prepare the Image

Preparing an image for printing involves:

-   -   1. Conversion of the Photo Image into a Print Image    -   2. Rotation of the Print Image (internal color space) to align        the output for the orientation of the printer    -   3. Up-interpolation of compressed channels (if necessary)    -   4. Color conversion from the internal color space to the CMY        color space appropriate to the specific printer and ink

The conversion of a Photo Image into a Print Image requires theexecution of a Vark script to perform image processing. The script iseither a default image enhancement script or a Vark script taken fromthe currently inserted Artcard. The Vark script is executed via the CPU,accelerated by functions performed by the VLIW Vector Processor.

The image in memory is originally oriented to be top upwards. Thisallows for straightforward Vark processing. Before the image is printed,it must be aligned with the print roll's orientation. The re-alignmentonly needs to be done once. Subsequent Prints of a Print Image willalready have been rotated appropriately.

The transformation to be applied is simply the inverse of that appliedduring capture from the CCD when the user pressed the “Image Capture”button on the Artcam. If the original rotation was 0, then notransformation needs to take place. If the original rotation was +90degrees, then the rotation before printing needs to be −90 degrees (sameas 270 degrees). The method used to apply the rotation is the Varkaccelerated Affine Transform function.

The Lab image must be converted to CMY before printing. Differentprocessing occurs depending on whether the a and b channels of the Labimage is compressed. If the Lab image is compressed, the a and bchannels must be decompressed before the color conversion occurs. If theLab image is not compressed, the color conversion is the only necessarystep. The Lab image must be up interpolated (if the a and b channels arecompressed) and converted into a CMY image. A single VLIW processcombining scale and color transform can be used.

Printing an image is concerned with taking a correctly oriented CMYimage, and generating data and signals to be sent to the external PrintHead. The process involves the CPU working in conjunction with a VLIWprocess and the Print Head Interface.

One VLIW process is responsible for calculating the next of dots to beprinted. Odd and even C, M, and Y dots are generated by dithering inputCMY image lines. A second VLIW process is responsible for taking apreviously calculated line of dots, and correctly generating 8 bits ofdata for the 8 segments to be transferred by the Print Head Interface tothe Print Head in a single transfer.

The Print Head Interface takes the 8 bit data from the VLIW Output FIFO,and outputs it unchanged to the Print Head The CPU also controls thevarious motors and guillotine via the parallel interface during theprint process.

V. Data Card Reader

FIG. 25 illustrates a card reader 500 which allows for the insertion ofArtcards 9 for reading. FIG. 24 shows an exploded perspective of thereader of FIG. 25. The cardreader 500 is interconnected to a computersystem and includes a CCD reading mechanism 35. The cardreader includespinch rollers 506, 507 for pinching an inserted Artcard 9. One of theroller e.g. 506 is driven by an Artcard motor 37 for the advancement ofthe card 9 between the two rollers 506 and 507 at a uniformed speed.

The Artcard 9 is passed over a series of LED lights 512 which areencased within a clear plastic mould 514 having a semi circular crosssection. The cross section focuses the light from the LEDs eg 512 ontothe surface of the card 9 as it passes by the LEDs 512. From the surfaceit is reflected to a high resolution linear CCD 34 which is constructedto a resolution of approximately 480 dpi. The surface of the Artcard 9is encoded to the level of approximately 1600 dpi hence, the linear CCD34 supersamples the Artcard surface with an approximately three timesmultiplier. The Artcard 9 is further driven at a speed such that thelinear CCD 34 is able to supersample in the direction of Artcardmovement at a rate of approximately 4800 readings per inch. The scannedArtcard CCD data is forwarded from the Artcard reader to ACP 31 forprocessing. A sensor 49, which can comprise a light sensor acts todetect of the presence of the card 13.

To assist reading, the data surface area of the Artcard 9 is modulatedwith a checkerboard pattern as previously discussed with reference toFIG. 12. Other forms of high frequency modulation may be possiblehowever.

It will be evident that an Artcard printer can be provided as for theprinting out of data on storage Artcard. Hence, the Artcard system canbe utilized as a general form of information distribution outside of theArtcam device. An Artcard printer can prints out Artcards on highquality print surfaces and multiple Artcards can be printed on samesheets and later separated. On a second surface of the Artcard 9 can beprinted information relating to the files etc. stored on the Artcard 9for subsequent storage.

Hence, the Artcard system allows for a simplified form of storage whichis suitable for use in place of other forms of storage such as CD ROMs,magnetic disks etc. The Artcards 9 can also be mass produced and therebyproduced in a substantially inexpensive form for redistribution.

VI. Print Rolls

Turning to FIG. 26, there is illustrated the print roll 42 andprint-head portions of the Artcam. The paper/film 611 is fed in acontinuous “web-like” process to a printing mechanism 15 which includesfurther pinch rollers 616-619 and a print head 44

The pinch roller 613 is connected to a drive mechanism (not shown) andupon rotation of the print roller 613, “paper” in the form of film 611is forced through the printing mechanism 615 and out of the pictureoutput slot 6. A rotary guillotine mechanism (not shown) is utilised tocut the roll of paper 611 at required photo sizes.

The printer roll 42 is responsible for supplying “paper” 611 to theprint mechanism 615 for printing of photographically imaged pictures.

In FIG. 27, there is shown an exploded perspective of the print roll 42.The printer roll 42 includes output printer paper 611 which is outputunder the operation of pinching rollers 612, 613.

Referring now to FIG. 28, there is illustrated a more fully explodedperspective view, of the print roll 42 of FIG. 27 without the “paper”film roll. The print roll 42 includes three main parts comprising inkreservoir section 620, paper roll sections 622, 623 and outer casingsections 626, 627.

Turning first to the ink reservoir section 620, which includes the inkreservoir or ink supply sections 633. The ink for printing is containedwithin three bladder type containers 630-632. The printer roll 42 isassumed to provide full color output inks. Hence, a first ink reservoiror bladder container 630 contains cyan colored ink. A second reservoir631 contains magenta colored ink and a third reservoir 632 containsyellow ink. Each of the reservoirs 630-632, although having differentvolumetric dimensions, are designed to have substantially the samevolumetric size.

The ink reservoir sections 621, 633, in addition to cover 624 can bemade of plastic sections and are designed to be mated together by meansof heat sealing, ultra violet radiation, etc. Each of the equally sizedink reservoirs 630-632 is connected to a corresponding ink channel639-641 for allowing the flow of ink from the reservoir 630-632 to acorresponding ink output port 635-637. The ink reservoir 632 having inkchannel 641, and output port 637, the ink reservoir 631 having inkchannel 640 and output port 636, and the ink reservoir 630 having inkchannel 639 and output port 637.

In operation, the ink reservoirs 630-632 can be filled withcorresponding ink and the section 633 joined to the section 621. The inkreservoir sections 630-632, being collapsible bladders, allow for ink totraverse ink channels 639-641 and therefore be in fluid communicationwith the ink output ports 635-637. Further, if required, an air inletport can also be provided to allow the pressure associated with inkchannel reservoirs 630-632 to be maintained as required.

The cap 624 can be joined to the ink reservoir section 620 so as to forma pressurized cavity, accessible by the air pressure inlet port.

The ink reservoir sections 621, 633 and 624 are designed to be connectedtogether as an integral unit and to be inserted inside printer rollsections 622, 623. The printer roll sections 622, 623 are designed tomate together by means of a snap fit by means of male portions 645-647mating with corresponding female portions (not shown). Similarly, femaleportions 654-656 are designed to mate with corresponding male portions660-662. The paper roll sections 622, 623 are therefore designed to besnapped together. One end of the film within the role is pinched betweenthe two sections 622, 623 when they are joined together. The print filmcan then be rolled on the print roll sections 622, 625 as required.

As noted previously, the ink reservoir sections 620, 621, 633, 624 aredesigned to be inserted inside the paper roll sections 622, 623. Theprinter roll sections 622, 623 are able to be rotatable aroundstationery ink reservoir sections 621, 633 and 624 to dispense film ondemand.

The outer casing sections 626 and 627 are further designed to be coupledaround the print roller sections 622, 623. In addition to each end ofpinch rollers eg 612, 613 is designed to clip in to a correspondingcavity eg 670 in cover 626, 627 with roller 613 being driven externally(not shown) to feed the print film and out of the print roll.

Finally, a cavity 677 can be provided in the ink reservoir sections 620,621 for the insertion and gluing of an silicon chip integrated circuittype device 53 for the storage of information associated with the printroll 42.

As shown in FIG. 23 and FIG. 28, the print roll 42 is designed to beinserted into the Artcam camera device so as to couple with a couplingunit 680 which includes connector pads 681 for providing a connectionwith the silicon chip 53. Further, the connector 680 includes endconnectors of four connecting with ink supply ports 635-637. The inksupply ports are in turn to connect to ink supply lines eg 682 which arein turn interconnected to printheads supply ports eg. 687 for the flowof ink to print-head 44 in accordance with requirements.

The “media” 611 utilised to form the roll can comprise many differentmaterials on which it is designed to print suitable images. For example,opaque rollable plastic material may be utilized, transparencies may beused by using transparent plastic sheets, metallic printing can takeplace via utilization of a metallic sheet film. Further, fabrics couldbe utilised within the printer roll 42 for printing images on fabric,although care must be taken that only fabrics having a suitablestiffness or suitable backing material are utilised.

When the print media is plastic, it can be coated with a layer whichfixes and absorbs the ink. Further, several types of print media may beused, for example, opaque white matte, opaque white gloss, transparentfilm, frosted transparent film, lenticular array film for stereoscopic3D prints, metallised film, film with the embossed optical variabledevices such as gratings or holograms, media which is pre-printed on thereverse side, and media which includes a magnetic recording layer. Whenutilising a metallic foil, the metallic foil can have a polymer base,coated with a thin (several micron) evaporated layer of aluminum orother metal and then coated with a clear protective layer adapted toreceive the ink via the ink printer mechanism.

In use the print roll 42 is obviously designed to be inserted inside acamera device so as to provide ink and paper for the printing of imageson demand. The ink output ports 635-637 meet with corresponding portswithin the camera device and the pinch rollers 672, 673 are operated toallow the supply of paper to the camera device under the control of thecamera device.

As illustrated in FIG. 28, a mounted silicon chip 53 is insert in oneend of the print roll 42. In FIG. 29 the authentication chip 53 is shownin more detail and includes four communications leads 680-683 forcommunicating details from the chip 53 to the corresponding camera towhich it is inserted.

Turning to FIG. 29, the chip can be separately created by means ofencasing a small integrated circuit 687 in epoxy and running bondingleads eg. 688 to the external communications leads 680-683. Theintegrated chip 687 being approximately 400 microns square with a 100micron scribe boundary. Subsequently, the chip can be glued to anappropriate surface of the cavity of the print roll 42. In FIG. 30,there is illustrated the integrated circuit 687 interconnected tobonding pads 681, 682 in an exploded view of the arrangement of FIG. 29.

VII. Authentication Chip

The authentication chip 53 of the preferred embodiment is responsiblefor ensuring that only correctly manufactured print rolls are utilizedin the camera system. The authentication chip 53 utilizes technologiesthat are generally valuable when utilized with any consumables and arenot restricted to print roll system. Manufacturers of other systems thatrequire consumables (such as a laser printer that requires tonercartridges) have struggled with the problem of authenticatingconsumables, to varying levels of success. Most have resorted tospecialized packaging. However this does not stop home refill operationsor clone manufacture. The prevention of copying is important to preventpoorly manufactured substitute consumables from damaging the basesystem. For example, poorly filtered ink may clog print nozzles in anink jet printer, causing the consumer to blame the system manufacturerand not admit the use of non-authorized consumables.

To solve the authentication problem, the Authentication chip 53 containsan authentication code and circuit specially designed to preventcopying. The chip is manufactured using the standard Flash memorymanufacturing process, and is low cost enough to be included inconsumables such as ink and toner cartridges. The Authentication chip 53ideally must have a low manufacturing cost in order to be included asthe authentication mechanism for low cost consumables. TheAuthentication chip 53 should use a standard manufacturing process, suchas Flash. This is necessary to:

-   -   Allow a great range of manufacturing location options    -   Use well-defined and well-behaved technology    -   Reduce cost

Regardless of the authentication scheme used, the circuitry of theauthentication part of the chip must be resistant to physical attack.Physical attack comes in four main ways, although the form of the attackcan vary:

-   -   Bypassing the Authentication Chip altogether    -   Physical examination of chip while in operation (destructive and        non-destructive)    -   Physical decomposition of chip    -   Physical alteration of chip

The Authentication Chip has a physical and a logical external interface.The physical interface defines how the Authentication Chip can beconnected to a physical System, and the logical interface determines howthat System can communicate with the Authentication Chip.

Physical Interface

The Authentication Chip is a small 4-pin CMOS package (actual internalsize is approximately 0.30 mm² using 0.25 μm Flash process). The 4 pinsare GND, CLK, Power, and Data. Power is a nominal voltage. If thevoltage deviates from this by more than a fixed amount, the chip willRESET. The recommended clock speed is 4-10 MHz. Internal circuitryfilters the clock signal to ensure that a safe maximum clock speed isnot exceeded. Data is transmitted and received one bit at a time alongthe serial data line. The chip performs a RESET upon power-up,power-down. In addition, tamper detection and prevention circuitry inthe chip will cause the chip to either RESET or erase Flash memory(depending on the attack detected) if an attack is detected. A specialProgramming Mode is enabled by holding the CLK voltage at a particularlevel.

Logical Interface

The Authentication Chip has two operating modes—a Normal Mode and aProgramming Mode. The two modes are required because the operatingprogram code is stored in Flash memory instead of ROM (for securityreasons). The Programming mode is used for testing purposes aftermanufacture and to load up the operating program code, while the normalmode is used for all subsequent usage of the chip.

The Programming Mode is enabled by holding a specific voltage on the CLKline for a given amount of time. When the chip enters Programming Mode,all Flash memory is erased (including all secret key information and anyprogram code). The Authentication Chip then validates the erasure. Ifthe erasure was successful, the Authentication Chip receives 384 bytesof data corresponding to the new program code. The bytes are transferredin order byte₀ to byte₃₈₃. The bits are transferred from bit₀ to bit₇.Once all 384 bytes of program code have been loaded, the AuthenticationChip hangs. If the erasure was not successful, the Authentication Chipwill hang without loading any data into the Flash memory. After the chiphas been programmed, it can be restarted. When the chip is RESET with anormal voltage on the CLK line, Normal Mode is entered.

Whenever the Authentication Chip is not in Programming Mode, it is inNormal Mode. When the Authentication Chip starts up in Normal Mode (forexample a power-up RESET), it executes the program currently stored inthe program code region of Flash memory. The program code implements acommunication mechanism between the System and Authentication Chip,accepting commands and data from the System and producing output values.Since the Authentication Chip communicates serially, bits aretransferred one at a time. The System communicates with theAuthentication Chips via a simple operation command set.

VIII. Image Organization

Three logical types of images are manipulated by the ACP. They are:

-   -   CCD Images, such as the Input Image captured from the CCD.    -   Internal Format Images, utilised internally by the Artcam        device.    -   Print Images, which is the Output Image format printed by the        Artcam

These images are typically different in color space, resolution, and theoutput & input color spaces which can vary from camera to camera. Forexample, a CCD image on a low-end camera may be a different resolution,or have different color characteristics from that used in a high-endcamera. However all internal image formats are the same format in termsof color space across all cameras.

In addition, the three image types can vary with respect to whichdirection is ‘up’. The physical orientation of the camera causes thenotion of a portrait or landscape image, and this must be maintainedthroughout processing. For this reason, the internal image is alwaysoriented correctly, and rotation is performed on images obtained fromthe CCD and during the print operation.

Other than the final Print Image, images in the Artcam are typically notcompressed. Because of memory constraints, software may choose tocompress the final Print Image in the chrominance channels by scalingeach of these channels by 2:1. If this has been done, the PRINT Varkfunction call utilised to print an image must be told to treat thespecified chrominance channels as compressed. The PRINT function is theonly function that knows how to deal with compressed chrominance, andeven so, it only deals with a fixed 2:1 compression ratio.

Although it is possible to compress an image and then operate on thecompressed image to create the final print image, it is not recommendeddue to a loss in resolution. In addition, an image should only becompressed once—as the final stage before printout. While onecompression is virtually undetectable, multiple compressions may causesubstantial image degradation.

Clip images stored on Artcards have no explicit support by the ACP 31.Software is responsible for taking any images from the current Artcardand organizing the data into a form known by the ACP. If images arestored compressed on an Artcard, software is responsible fordecompressing them, as there is no specific hardware support fordecompression of Artcard images.

During brushing, tiling, and warping processes utilised to manipulate animage, it is often necessary to compute the average color of aparticular area in an image. Rather than calculate the value for eacharea given, these functions make use of an image pyramid. As illustratedin FIG. 7, an image pyramid is effectively a multi-resolution pixel-map.The original image 115 is a 1:1 representation. Low-pass filtering andsub-sampling by 2:1 in each dimension produces an image ¼ the originalsize 116. This process continues until the entire image is representedby a single pixel. An image pyramid is constructed from an originalinternal format image, and consumes ⅓ of the size taken up by theoriginal image (¼+ 1/16+ 1/64+ . . . ). For an original image of1500×1000 the corresponding image pyramid is approximately ½ MB. Animage pyramid is constructed by a specific Vark function, and is used asa parameter to other Vark functions.

The entire processed image is required at the same time in order toprint it. However the Print Image output can comprise a CMY ditheredimage and is only a transient image format, used within the Print Imagefunctionality. However, it should be noted that color conversion willneed to take place from the internal color space to the print colorspace. In addition, color conversion can be tuned to be different fordifferent print rolls in the camera with different ink characteristicse.g. Sepia output can be accomplished by using a specific sepia toningArtcard, or by using a sepia tone print-roll (so all Artcards will workin sepia tone).

3 color spaces used in the Artcam, corresponding to the different imagetypes. The ACP has no direct knowledge of specific color spaces.Instead, it relies on client color space conversion tables to convertbetween CCD, internal, and printer color spaces:

-   -   CCD:RGB    -   Internal:Lab    -   Printer:CMY

Removing the color space conversion from the ACP 31 allows:

-   -   Different CCDs to be used in different cameras    -   Different inks (in different print rolls over time) to be used        in the same camera    -   Separation of CCD selection from ACP design path    -   A well defined internal color space for accurate color        processing

IX. Print Head Unit

Turning now to FIG. 31, there is illustrated an exploded perspectiveview, partly in section, of the print head unit 615 of FIG. 26.

The print head unit 615 is based around the print-head 44 which ejectsink drops on demand on to print media 611 so as to form an image. Theprint media 611 is pinched between two set of rollers comprising a firstset 618, 616 and second set 617, 619.

The print-head 44 operates under the control of power, ground and signallines 810 which provides power and control for the print-head 44 and arebonded by means of Tape Automated Bonding (TAB) to the surface of theprint-head 44.

Importantly, the print-head 44 which can be constructed from a siliconwafer device suitably separated, relies upon a series of anisotropicetches 812 through the wafer having near vertical side walls. Thethrough wafer etches 812 allow for the direct supply of ink to theprint-head surface from the back of the wafer for subsequent ejection.

The ink is supplied to the back of the inkjet print-head 44 by means ofink-head supply unit 814. The inkjet print-head 44 has three separaterows along its surface for the supply of separate colors of ink. Theink-head supply unit 814 also includes a lid 815 for the sealing of inkchannels.

In FIG. 32 to FIG. 34, there is illustrated various perspective views ofthe ink-head supply unit 814. Each of FIG. 32 to FIG. 34 illustrate onlya portion of the ink head supply unit which can be constructed ofindefinite length, the portions shown so as to provide exemplarydetails. In FIG. 32 there is illustrated a bottom perspective view, FIG.21 illustrates a top perspective view, FIG. 33 illustrates a close upbottom perspective view, partly in section, FIG. 34 illustrates a topside perspective view showing details of the ink channels, and FIG. 35illustrates a top side perspective view as does FIG. 36.

There is considerable cost advantage in forming ink-head supply unit 814from injection molded plastic instead of, say, micromachined silicon.The manufacturing cost of a plastic ink channel will be considerablyless in volume and manufacturing is substantially easier. The designillustrated in the accompanying Figures assumes a 1600 dpi three colormonolithic print head, of a predetermined length. The provided flow ratecalculations are for a 100 mm photo printer.

The ink-head supply unit 814 contains all of the required fine details.The lid 815 (FIG. 31) is permanently glued or ultrasonically welded tothe ink-head supply unit 814 and provides a seal for the ink channels.

Turning to FIG. 33, the cyan, magenta and yellow ink flows in throughink inlets 820-822, the magenta ink flows through the throughholes824,825 and along the magenta main channels 826,827 (FIG. 20). The cyanink flows along cyan main channel 830 and the yellow ink flows along theyellow main channel 831. As best seen from FIG. 33, the cyan ink in thecyan main channels then flows into a cyan sub-channel 833. The yellowsubchannel 834 similarly receiving yellow ink from the yellow mainchannel 831.

As best seen in FIG. 34, the magenta ink also flows from magenta mainchannels 826,827 through magenta throughholes 836, 837. Returning againto FIG. 33, the magenta ink flows out of the throughholes 836, 837. Themagenta ink flows along first magenta subchannel e.g. 838 and then alongsecond magenta subchannel e.g. 839 before flowing into a magenta trough840. The magenta ink then flows through magenta vias e.g. 842 which arealigned with corresponding inkjet head throughholes (e.g. 812 of FIG.30) wherein they subsequently supply ink to inkjet nozzles for printingout.

Similarly, the cyan ink within the cyan subchannel 833 flows into a cyanpit area 849 which supplies ink two cyan vias 843, 844. Similarly, theyellow subchannel 834 supplies yellow pit area 46 which in turn suppliesyellow vias 847, 848.

As seen in FIG. 34, the print-head is designed to be received withinprint-head slot 850 with the various vias e.g. 851 aligned withcorresponding through holes eg. 851 in the print-head wafer.

Returning to FIG. 31, care must be taken to provide adequate ink flow tothe entire print-head chip 44, while satisfying the constraints of aninjection moulding process. The size of the ink through wafer holes 812at the back of the print head chip is approximately 100 μm×50 μm, andthe spacing between through holes carrying different colors of ink isapproximately 170 μm. While features of this size can readily be moldedin plastic (compact discs have micron sized features), ideally the wallheight must not exceed a few times the wall thickness so as to maintainadequate stiffness. The preferred embodiment overcomes these problems byusing hierarchy of progressively smaller ink channels.

In FIG. 35, there is illustrated a small portion 870 of the surface ofthe print-head 44. The surface is divided into 3 series of nozzlescomprising the cyan series 871, the magenta series 872 and the yellowseries 873. Each series of nozzles is further divided into two rows eg.875, 876 with the print-head 44 having a series of bond pads 878 forbonding of power and control signals.

The print head is preferably constructed in accordance with a largenumber of different forms of ink jet invented for uses including Artcamdevices. These ink jet devices are discussed in further detailhereinafter.

The print-head nozzles include the ink supply channels 880, equivalentto anisotropic etch hole 812 of FIG. 31. The ink flows from the back ofthe wafer through supply channel 881 and in turn through the filtergrill 882 to ink nozzle chambers eg. 883. The operation of the nozzlechamber 883 and print-head 44 (FIG. 1) is, as mentioned previously,described in the abovementioned patent specification.

X. Postcard Print Rolls

Turning now to FIG. 37, in one form of the preferred embodiment, theoutput printer paper 11 can, on the side that is not to receive theprinted image, contain a number of pre-printed “postcard” formattedbacking portions 885. The postcard formatted sections 885 can includeprepaid postage “stamps” 886 which can comprise a printed authorizationfrom the relevant postage authority within whose jurisdiction the printroll is to be sold or utilised. By agreement with the relevantjurisdictional postal authority, the print rolls can be made availablehaving different postages. This is especially convenient where overseastravelers are in a local jurisdiction and wishing to send a number ofpostcards to their home country. Further, an address format portion 887is provided for the writing of address dispatch details in the usualform of a postcard. Finally, a message area 887 is provided for thewriting of a personalized information.

Turning now to FIG. 37 and FIG. 38, the operation of the camera deviceis such that when a series of images 890-892 is printed on a firstsurface of the print roll, the corresponding backing surface is thatillustrated in FIG. 37. Hence, as each image eg. 891 is printed by thecamera, the back of the image has a ready made postcard 885 which can beimmediately dispatched at the nearest post office box within thejurisdiction. In this way, personalized postcards can be created.

It would be evident that when utilising the postcard system asillustrated in FIG. 38 and FIG. 39 only predetermined image sizes arepossible as the synchronization between the backing postcard portion 885and the front image 891 must be maintained. This can be achieved byutilising the memory portions of the authentication chip stored withinthe print roll to store details of the length of each postcard backingformat sheet 885. This can be achieved by either having each postcardthe same size or by storing each size within the print rolls on-boardprint chip memory.

The Artcam camera control system can ensure that, when utilising a printroll having pre-formatted postcards, that the printer roll is utilisedonly to print images such that each image will be on a postcardboundary. Of course, a degree of “play” can be provided by providingborder regions at the edges of each photograph which can account forslight misalignment.

Turning now to FIG. 39, it will be evident that postcard rolls can bepre-purchased by a camera user when traveling within a particularjurisdiction where they are available. The postcard roll can, on itsexternal surface, have printed information including country ofpurchase, the amount of postage on each postcard, the format of eachpostcard (for example being C, H or P or a combination of these imagemodes), the countries that it is suitable for use with and the postageexpiry date after which the postage is no longer guaranteed to besufficient can also be provided.

Hence, a user of the camera device can produce a postcard for dispatchin the mail by utilising their hand held camera to point at a relevantscene and taking a picture having the image on one surface and thepre-paid postcard details on the other. Subsequently, the postcard canbe addressed and a short message written on the postcard before itsimmediate dispatch in the mail.

XI. Software Operation

In respect of the software operation of the Artcam device, although manydifferent software designs are possible, in one design, each Artcamdevice can consist of a set of loosely coupled functional modulesutilised in a coordinated way by a single embedded application to servethe core purpose of the device. While the functional modules are reusedin different combinations in various classes of Artcam device, theapplication is specific to the class of Artcam device.

Most functional modules contain both software and hardware components.The software is shielded from details of the hardware by a hardwareabstraction layer, while users of a module are shielded from itssoftware implementation by an abstract software interface. Because thesystem as a whole is driven by user-initiated and hardware-initiatedevents, most modules can run one or more asynchronous event-drivenprocesses.

The most important modules which comprise the generic Artcam device areshown in FIG. 40. In this and subsequent diagrams, software componentsare shown on the left separated by a vertical dashed line 901 fromhardware components on the right. The software aspects of these modulesare described below:

Software Modules—Artcam Application 902

The Artcam Application implements the high-level functionality of theArtcam device. This normally involves capturing an image, applying anartistic effect to the image, and then printing the image. In acamera-oriented Artcam device, the image is captured via the CameraManager 903. In a printer-oriented Artcam device, the image is capturedvia the Network Manager 904, perhaps as the result of the image being“squirted” by another device.

Artistic effects are found within the unified file system managed by theFile Manager 905. An artistic effect consist of a script file and a setof resources. The script is interpreted and applied to the image via theImage Processing Manager 906. Scripts are normally shipped on ArtCardsknown as Artcards. By default the application uses the script containedon the currently mounted Artcard.

The image is printed via the Printer Manager 908. When the Artcam devicestarts up, the bootstrap process starts the various manager processesbefore starting the application. This allows the application toimmediately request services from the various managers when it starts.

Where the camera includes a display, the application also constructs agraphical user interface via the User Interface Manager 910 which allowsthe user to edit the current date and time, and other editable cameraparameters. The application saves all persistent parameters in flashmemory.

Real-Time Microkernel 911

The Real-Time Microkernel schedules processes preemptively on the basisof interrupts and process priority. It provides integrated inter-processcommunication and timer services, as these are closely tied to processscheduling. All other operating system functions are implemented outsidethe microkernel.

Camera Manager 903

The Camera Manager provides image capture services. It controls thecamera hardware embedded in the Artcam. It provides an abstract cameracontrol interface which allows camera parameters to be queried and set,and images captured. This abstract interface decouples the applicationfrom details of camera implementation

The Camera Manager runs as an asynchronous event-driven process. Itcontains a set of linked state machines, one for each asynchronousoperation. These include auto focussing, charging the flash, countingdown the self-timer, and capturing the image. On initialization theCamera Manager sets the camera hardware to a known state. This includessetting a normal focal distance and retracting the zoom. The softwarestructure of the Camera Manager is illustrated in FIG. 41. The softwarecomponents are described in the following subsections:

Lock Focus 913

Lock Focus automatically adjusts focus and exposure for the currentscene, and enables the flash if necessary, depending on the focuscontrol mode, exposure control mode and flash mode. Lock Focus isnormally initiated in response to the user pressing the Take buttonhalfway. It is part of the normal image capture sequence, but may beseparated in time from the actual capture of the image, if the userholds the take button halfway depressed. This allows the user to do spotfocusing and spot metering.

Capture Image 914

Capture Image captures an image of the current scene. It lights ared-eye lamp if the flash mode includes red-eye removal, controls theshutter, triggers the flash if enabled, and senses the image through theimage sensor. It determines the orientation of the camera, and hence thecaptured image, so that the image can be properly oriented during laterimage processing. It also determines the presence of camera motionduring image capture, to trigger deblurring during later imageprocessing.

Self-Timed Capture 915

Self-Timed Capture captures an image of the current scene after countingdown a 20 s timer. It gives the user feedback during the countdown viathe self-timer LED. During the first 15 s it can light the LED. Duringthe last 5 s it flashes the LED.

View Scene 917

View Scene periodically senses the current scene through the imagesensor and displays it on the color LCD, giving the user an LCD-basedviewfinder.

Auto Focus 918

Auto Focus changes the focal length until selected regions of the imageare sufficiently sharp to signify that they are in focus. It assumes theregions are in focus if an image sharpness metric derived from specifiedregions of the image sensor is above a fixed threshold. It finds theoptimal focal length by performing a gradient descent on the derivativeof sharpness by focal length, changing direction and stepsize asrequired. If the focus control mode is multi-point auto, then threeregions are used, arranged horizontally across the field of view. If thefocus control mode is single-point auto, then one region is used, in thecenter of the field of view. Auto Focus works within the available focallength range as indicated by the focus controller. In fixed-focusdevices it is therefore effectively disabled.

Auto Flash 919

Auto Flash determines if scene lighting is dim enough to require theflash. It assumes the lighting is dim enough if the scene lighting isbelow a fixed threshold. The scene lighting is obtained from thelighting sensor, which derives a lighting metric from a central regionof the image sensor. If the flash is required, then it charges theflash.

Auto Exposure 920

The combination of scene lighting, aperture, and shutter speed determinethe exposure of the captured image. The desired exposure is a fixedvalue. If the exposure control mode is auto, Auto Exposure determines acombined aperture and shutter speed which yields the desired exposurefor the given scene lighting. If the exposure control mode is aperturepriority, Auto Exposure determines a shutter speed which yields thedesired exposure for the given scene lighting and current aperture. Ifthe exposure control mode is shutter priority, Auto Exposure determinesan aperture which yields the desired exposure for the given scenelighting and current shutter speed. The scene lighting is obtained fromthe lighting sensor, which derives a lighting metric from a centralregion of the image sensor.

Auto Exposure works within the available aperture range and shutterspeed range as indicated by the aperture controller and shutter speedcontroller. The shutter speed controller and shutter controller hide theabsence of a mechanical shutter in most Artcam devices.

If the flash is enabled, either manually or by Auto Flash, then theeffective shutter speed is the duration of the flash, which is typicallyin the range 1/1000 s to 1/10000 s.

Image Processing Manager 906 (FIG. 40)

The Image Processing Manager provides image processing and artisticeffects services. It utilises the VLIW Vector Processor embedded in theArtcam to perform high-speed image processing. The Image ProcessingManager contains an interpreter for scripts written in the Vark imageprocessing language. An artistic effect therefore consists of a Varkscript file and related resources such as fonts, clip images etc. Thesoftware structure of the Image Processing Manager is illustrated inmore detail in FIG. 42 and include the following modules:

Convert and Enhance Image 921

The Image Processing Manager performs image processing in thedevice-independent CIE LAB color space, at a resolution which suits thereproduction capabilities of the Artcam printer hardware. The capturedimage is first enhanced by filtering out noise. It is optionallyprocessed to remove motion-induced blur. The image is then convertedfrom its device-dependent RGB color space to the CIE LAB color space. Itis also rotated to undo the effect of any camera rotation at the time ofimage capture, and scaled to the working image resolution. The image isfurther enhanced by scaling its dynamic range to the available dynamicrange.

Detect Faces 923

Faces are detected in the captured image based on hue and local featureanalysis. The list of detected face regions is used by the Vark scriptfor applying face-specific effects such as warping and positioningspeech balloons.

Vark Image Processing Language Interpreter 924

Vark consists of a general-purpose programming language with a rich setof image processing extensions. It provides a range of primitive datatypes (integer, real, boolean, character), a range of aggregate datatypes for constructing more complex types (array, string, record), arich set of arithmetic and relational operators, conditional anditerative control flow (if-then-else, while-do), and recursive functionsand procedures. It also provides a range of image-processing data types(image, clip image, matte, color, color lookup table, palette, dithermatrix, convolution kernel, etc.), graphics data types (font, text,path), a set of image-processing functions (color transformations,compositing, filtering, spatial transformations and warping,illumination, text setting and rendering), and a set of higher-levelartistic functions (tiling, painting and stroking).

A Vark program is portable in two senses. Because it is interpreted, itis independent of the CPU and image processing engines of its host.Because it uses a device-independent model space and adevice-independent color space, it is independent of the input colorcharacteristics and resolution of the host input device, and the outputcolor characteristics and resolution of the host output device.

The Vark Interpreter 924 parses the source statements which make up theVark script and produces a parse tree which represents the semantics ofthe script. Nodes in the parse tree correspond to statements,expressions, sub-expressions, variables and constants in the program.The root node corresponds to the main procedure statement list.

The interpreter executes the program by executing the root statement inthe parse tree. Each node of the parse tree asks its children toevaluate or execute themselves appropriately. An if statement node, forexample, has three children—a condition expression node, a thenstatement node, and an else statement node. The if statement asks thecondition expression node to evaluate itself, and depending on theboolean value returned asks the then statement or the else statement toexecute itself. It knows nothing about the actual condition expressionor the actual statements.

While operations on most data types are executed during execution of theparse tree, operations on image data types are deferred until afterexecution of the parse tree. This allows imaging operations to beoptimized so that only those intermediate pixels which contribute to thefinal image are computed. It also allows the final image to be computedin multiple passes by spatial subdivision, to reduce the amount ofmemory required.

During execution of the parse tree, each imaging function simply returnsan imaging graph—a graph whose nodes are imaging operators and whoseleaves are images—constructed with its corresponding imaging operator asthe root and its image parameters as the root's children. The imageparameters are of course themselves image graphs. Thus each successiveimaging function returns a deeper imaging graph.

After execution of the parse tree, an imaging graph is obtained whichcorresponds to the final image. This imaging graph is then executed in adepth-first manner (like any expression tree), with the following twooptimizations: (1) only those pixels which contribute to the final imageare computed at a given node, and (2) the children of a node areexecuted in the order which minimizes the amount of memory required. Theimaging operators in the imaging graph are executed in the optimizedorder to produce the final image. Compute-intensive imaging operatorsare accelerated using the VLIW Processor embedded in the Artcam device.If the amount of memory required to execute the imaging graph exceedsavailable memory, then the final image region is subdivided until therequired memory no longer exceeds available memory.

For a well-constructed Vark program the first optimization is unlikelyto provide much benefit per se. However, if the final image region issubdivided, then the optimization is likely to provide considerablebenefit. It is precisely this optimization, then, that allowssubdivision to be used as an effective technique for reducing memoryrequirements. One of the consequences of deferred execution of imagingoperations is that program control flow cannot depend on image content,since image content is not known during parse tree execution. Inpractice this is not a severe restriction, but nonetheless must be bornein mind during language design.

The notion of deferred execution (or lazy evaluation) of imagingoperations is described by Guibas and Stolfi (Guibas, L. J., and J.Stolfi, “A Language for Bitmap Manipulation”, ACM Transactions onGraphics, Vol. 1, No. 3, July 1982, pp. 191-214). They likewiseconstruct an imaging graph during the execution of a program, and duringsubsequent graph evaluation propagate the result region backwards toavoid computing pixels which do not contribute to the final image.Shantzis additionally propagates regions of available pixels forwardsduring imaging graph evaluation (Shantzis, M. A., “A Model for Efficientand Flexible Image Computing”, Computer Graphics Proceedings, AnnualConference Series, 1994, pp. 147-154). The Vark Interpreter uses themore sophisticated multi-pass bi-directional region propagation schemedescribed by Cameron (Cameron, S., “Efficient Bounds in ConstructiveSolid Geometry”, IEEE Computer Graphics & Applications, Vol. 11, No. 3,May 1991, pp. 68-74). The optimization of execution order to minimisememory usage is due to Shantzis, but is based on standard compilertheory (Aho, A. V., R. Sethi, and J. D. Ullman, “Generating Code fromDAGs”, in Compilers: Principles, Techniques, and Tools, Addison-Wesley,1986, pp. 557-567,). The Vark Interpreter uses a more sophisticatedscheme than Shantzis, however, to support variable-sized image buffers.The subdivision of the result region in conjunction with regionpropagation to reduce memory usage is also due to Shantzis.

Printer Manager 908 (FIG. 40)

The Printer Manager provides image printing services. It controls theInk Jet printer hardware embedded in the Artcam. It provides an abstractprinter control interface which allows printer parameters to be queriedand set, and images printed. This abstract interface decouples theapplication from details of printer implementation.

The Printer Manager runs as an asynchronous event-driven process. Itcontains a set of linked state machines, one for each asynchronousoperation. These include printing the image and auto mounting the printroll. The software structure of the Printer Manager is illustrated inFIG. 43. The software components are described in the followingdescription:

Print Image 930

Print Image prints the supplied image. It uses the VLIW Processor toprepare the image for printing. This includes converting the image colorspace to device-specific CMY and producing half-toned bi-level data inthe format expected by the print head.

Between prints, the paper is retracted to the lip of the print roll toallow print roll removal, and the nozzles can be capped to prevent inkleakage and drying. Before actual printing starts, therefore, thenozzles are uncapped and cleared, and the paper is advanced to the printhead. Printing itself consists of transferring line data from the VLIWprocessor, printing the line data, and advancing the paper, until theimage is completely printed. After printing is complete, the paper iscut with the guillotine and retracted to the print roll, and the nozzlesare capped. The remaining media length is then updated in the printroll.

Auto Mount Print Roll 131

Auto Mount Print Roll responds to the insertion and removal of the printroll. It generates print roll insertion and removal events which arehandled by the application and used to update the status display. Theprint roll is authenticated according to a protocol between theauthentication chip embedded in the print roll and the authenticationchip embedded in Artcam. If the print roll fails authentication then itis rejected. Various information is extracted from the print roll. Paperand ink characteristics are used during the printing process. Theremaining media length and the fixed page size of the media, if any, arepublished by the Print Manager and are used by the application.

User Interface Manager 910 (FIG. 40)

The User Interface Manager is illustrated in more detail if FIG. 44 andprovides user interface management services. It consists of a PhysicalUser Interface Manager 911, which controls status display and inputhardware, and a Graphical User Interface Manager 912, which manages avirtual graphical user interface on the color display. The UserInterface Manager translates virtual and physical inputs into events.Each event is placed in the event queue of the process registered forthat event.

File Manager 905 (FIG. 41)

The File Manager provides file management services. It provides aunified hierarchical file system within which the file systems of allmounted volumes appear. The primary removable storage medium used in theArtcam is the ArtCards. A ArtCards is printed at high resolution withblocks of bi-level dots which directly represent serror-tolerantReed-Solomon-encoded binary data. The block structure supports appendand append-rewrite in suitable read-write ArtCards devices (notinitially used in Artcam). At a higher level a ArtCards can contain anextended append-rewriteable ISO9660 CD-ROM file system. The softwarestructure of the File Manager, and the ArtCards Device Controller inparticular, can be as illustrated in FIG. 45.

Network Manager 904 (FIG. 41)

The Network Manager provides “appliance” networking services acrossvarious interfaces including infra-red (IrDA) and universal serial bus(USB). This allows the Artcam to share captured images, and receiveimages for printing.

Clock Manager 907 (FIG. 41)

The Clock Manager provides date and time-of-day clock services. Itutilises the battery-backed real-time clock embedded in the Artcam, andcontrols it to the extent that it automatically adjusts for clock drift,based on auto-calibration carried out when the user sets the time.

Power Management

When the system is idle it enters a quiescent power state during whichonly periodic scanning for input events occurs. Input events include thepress of a button or the insertion of a ArtCards. As soon as an inputevent is detected the Artcam device re-enters an active power state. Thesystem then handles the input event in the usual way.

Even when the system is in an active power state, the hardwareassociated with individual modules is typically in a quiescent powerstate. This reduces overall power consumption, and allows particularlydraining hardware components such as the printer's paper cuttingguillotine to monopolise the power source when they are operating. Acamera-oriented Artcam device is, by default, in image capture mode.This means that the camera is active, and other modules, such as theprinter, are quiescent. This means that when non-camera functions areinitiated, the application must explicitly suspend the camera module.Other modules naturally suspend themselves when they become idle.

Watchdog Timer

The system generates a periodic high-priority watchdog timer interrupt.The interrupt handler resets the system if it concludes that the systemhas not progressed since the last interrupt, i.e. that it has crashed.

Artcards can, of course, be used in many other environments. For exampleArtCards can be used in both embedded and personal computer (PC)applications, providing a user-friendly interface to large amounts ofdata or configuration information.

This leads to a large number of possible applications. For example, aArtCards reader can be attached to a PC. The applications for PCs aremany and varied. The simplest application is as a low cost read-onlydistribution medium. Since ArtCards are printed, they provide an audittrail if used for data distribution within a company.

Further, many times a PC is used as the basis for a closed system, yet anumber of configuration options may exist. Rather than rely on a complexoperating system interface for users, the simple insertion of a ArtCardsinto the ArtCards reader can provide all the configuration requirements.

While the back side of a ArtCards has the same visual appearanceregardless of the application (since it stores the data), the front of aArtCards is application dependent

It would be appreciated by a person skilled in the art that numerousvariations and/or modifications may be made to the present invention asshown in the specific embodiment without departing from the spirit orscope of the invention as broadly described. The present embodiment is,therefore, to be considered in all respects to be illustrative and notrestrictive.

1. A handheld camera comprising: a sensor adapted to sense an image; acamera manager for controlling the sensing of the image; an imageprocessing manager for manipulating the image; a print manager forcontrolling printing of the manipulated image; and a guillotine adaptedto cut a print media on which the manipulated image is printed from aprint roll, wherein the print manager is operable to activate theguillotine upon receipt of a signal indicative of an attempt to dispensethe print media at a rate greater than that of a print roll drive systemfor dispensing the print media.
 2. A handheld camera as claimed in claim1, further comprising a print roll sensor operable to indicate if theprint media is being dispensed at a rate greater than that of the printroll drive system.
 3. A handheld camera as claimed in claim 1, furthercomprising a print roll sensor adapted to detect an attempt to pullmedia from the camera.
 4. A handheld camera as claimed in claim 3,wherein the roll sensor is a strain guage sensor.